What in the Weather?

What in the Weather – Episode Summary Iowa Specialty Producers Conference | February 24, 2026 | Ankeny, Iowa This episode is a live recording of the What in the Weather podcast session presented at the Iowa Specialty Producers Conference. State Climatologist Justin Glisan and host Dan Fillius cover current weather conditions, a full 2025 weather year in review, and crop and pest impacts for Iowa specialty producers. Current Conditions & Outlook February 2025 has been one of the top five warmest on record; the state is now in a brief cool spell following a significant snowfall event near Waterloo (12–14 inches) Precipitation is at 72% of normal statewide, with northwestern Iowa below 50%; drought conditions are emerging and could worsen if dry weather continues The forecast for early March shows a warm and wet signal, which typically brings increased thunderstorm activity 2025 Weather Year in Review 2025 was the 25th warmest year on record (1.3°F above average); the past five years are the warmest five-year period on record June and July were exceptionally humid — dew points above 70°F were recorded on more than half of July's days, producing heat index values near 109°F The second wettest July on record was followed by a dry fall — Red Oak went 33 days without measurable precipitation Iowa recorded 36 tornadoes in 2025, below the average of 44, with no fatalities 2025 Weather Superlatives Coldest stretch: Feb. 10–22, with daytime highs as low as -20°F (NW Iowa) and a dew point of -29°F in Sioux County Warmest overnight low: 82°F in June (Quad Cities) Highest temperature: 101°F, Little Sioux (June 20) Coldest overnight low: -23°F, Fayette Biggest single rain event: 8.64 inches in Decorah Wettest location: Boone at 47.84 inches; driest: Randolph at 24.56 inches Longest growing season: southeastern Iowa; shortest: northwestern Iowa Crop Impacts Low winter precipitation in 2024–25 led to garlic winter damage on multiple farms Wet June and July caused widespread disease, delayed plantings, and poor early fruit set in tomatoes, peppers, and eggplant Worst-performing crops: onions (waterlogged soils), watermelons, and summer broccoli (heat and disease) Best-performing crop: tomatoes — scarce supply drove strong prices, with tunnel growers fetching ~$4/lb late in the season; late-planted fall carrots were a standout surprise Pest & Disease Highlights Top insect pests: aphids (especially damaging on fall and winter greens) and onion thrips  Top diseases: pepper anthracnose, Alternaria on brassicas, and southern rust in corn Management tips discussed include pre-transplant aphid dips with M-Pede or Suffoil-X, interplanting sweet alyssum to attract beneficials, and a conventional onion thrips spray rotation using Movento and Radiant per the 2026 Midwest Veg Guide Podcast summary generated using Claude.ai

Episode Summary Topics Covered: • 00:00:29 - Iowa Weather History (January 27-28, 1977): The devastating 1977 blizzard that struck northern and eastern Iowa with winds up to 55 mph, 6-foot snow drifts, and wind chills dropping to negative 60 to negative 90 • 00:01:32 - Weekly Weather Forecast: Warming trend ahead with temperatures climbing from teens/20s to the 30s by Monday/Tuesday; quiet storm track with most action on southern and eastern coasts of the country • 00:02:32 - Extended Climate Outlook (6-14 Days & Beyond): February 2-10 looking warm and dry for upper Midwest; discussion of Arctic Oscillation Index and its role in predicting cold air outbreaks 2-3 weeks in advance • 00:06:35 - February Weather Predictions: Analysis of weak La Niña patterns, snowpack comparisons (Siberia vs. Europe), and potential for more cold outbreaks and snowfall in second-half of February due to meridional flow • 00:09:02 - December 2025 & Year in Review: December was 65th coldest on record; November-December was 6th snowiest combined period in 130 years; 2025 was 25th warmest year on record with 2020s being warmest decade for Iowa • 00:12:24 - Climate Change & Polar Vortex Connection: How warming Arctic (3x faster than mid-latitudes) leads to more extreme cold air outbreaks; Des Moines is 5 degrees warmer in winter than 30 years ago; explanation of jet stream meanders and persistent weather patterns • 00:15:30 - Arctic Sea Ice & Feedback Loops: Discussion of albedo/reflectivity, salinity changes in Arctic Ocean, and how melting sea ice creates positive feedback warming cycle • 00:16:54 - Future Temperature Projections (2050-2071): Models show 20-30 days of 95°+ temperatures in summer with heat indices reaching 125-140°F; cold outbreaks will be less frequent but more extreme • 00:19:45 - Specialty Crop Impacts:  • 00:20:43 - Research Spotlight - Sumisansui Irrigation: Ben Phillips' (Michigan State) study on Japanese micro-perforation irrigation hoses; effectiveness for germination and cooling; limitations with wind susceptibility and vegetation blocking • 00:24:07 - Broccoli Production Master Class: Thomas Bjorkman's comprehensive presentation covering hollow stem issues, variety selection, spacing strategies, and the unique challenge of cooling meristematic tissue that generates heat even after harvest • 00:27:40 - Organic Veg Production Conference: Highlights from online conference including Flint Wiswall's (Cate Farm) innovative bench-moving systems for transplant production • 00:29:21 - Looking Ahead: Preview of next episode - the annual "best and worst" superlatives show recording from Iowa Specialty Producers Conference in late February Episode summary generated using claude.ai

Podcast Summary Weather History & Current Conditions (December 18, 2025) Historic perspective: December 18, 1976 saw unseasonably warm temps reaching 64°F in Des Moines Recent pattern shift from active Alberta Clippers bringing light, fluffy snow to warmer, drier conditions Flash freeze warning for today as cold front passes through with potential snow squalls White Christmas Outlook Historical probabilities: Rock Rapids (70%), Des Moines (39%), Fort Madison (30%) 2025 forecast: Unlikely for white Christmas anywhere in Iowa due to warming trend and dry forecast through month's end Reflects broader trend of warming winters and transition from snow to rain/mixed precipitation Climate Forecast Next 7 days: Unseasonably warm (40s) and dry as polar vortex retreats north 6-14 day outlook: Strong signal for above-normal temps and dry conditions across western Iowa January-March: Equal chances on temperature, lean wet for eastern Iowa quarter Spring outlook: Potential transition to ENSO neutral conditions (70% probability), similar to pleasant spring 2025? December Snow Recap Fourth snowiest November on record for some stations Keokuk Lock and Dam (records since 1894) and Toledo (records since 1884) saw snowiest November-December period Multiple Alberta Clippers dropped 2-3 inches each, totaling 5-7 inches statewide December 14th storm caused I-80 closures and treacherous driving conditions Specialty Crop Updates Melcast System: Fungicide timing tool for melon growers will be available for Iowa locations (web-based platform from Indiana) Caterpillar Tunnels: Rolling Acres Produce Supply in Drakesville now manufacturing local tunnel kits with prefab end walls with doors Great Lakes Expo Recap: Major Midwest fruit/vegetable conference in Grand Rapids  Annual Strawberry Production: New technique shared—rooting bare-root plants in plug trays for 6 weeks before July 15th planting optimizes yield and reduces runner management Upcoming Last episode of 2025 Live recording at Iowa Specialty Producers Conference, February 24th in Ankeny January episode will come, but unknown date right now. Podcast summary generated using claude.ai

Weather Forecast & Outlook: Alberta Clipper brings nose dive in temperatures with wind chills in negative teens to negative 20s Quiet storm track ahead with possible flurries Saturday night December outlook: below normal temperatures for entire state, slightly below normal precipitation for southern/western Iowa Recent Weather Highlights: Recent snowstorm (8.5" statewide average) makes November rank as 5th snowiest on record  Fort Dodge recorded up to 16.5 inches of snow November and fall 2025 both ran about 3-4°F above average 7th warmest fall in 153 years of record Specialty Crop Impacts: Managing overwintered greens in high tunnels during frigid temperatures - use supplemental heat, and internal covers When growing greens for overwintering in warm fall weather, aggressively vent tunnel warmth to slow crop growth. Strawberry mulching timing and techniques - wait for dormancy (several nights around 20°F) before applying straw or row cover This Day in Weather History: December 2-3, 1990: Major snowstorm dropped 6-15" across Iowa with blizzard conditions Winds gusted to 69 mph at Cresco University of Iowa bubble dome collapsed under heavy snow, causing $2 million in damage Other Topics: Iowa corn and soybean yields hit record highs (215 bu/acre corn, 65 bu/acre soybeans) Discussion of July cloudiness and potential impacts on melon yields in southeast Iowa

Weather Forecast: Big winter cooldown coming this weekend with lows in the teens and highs in the upper 20s-low 30s Potential snowfall of 1-5 inches across northern Iowa Saturday into Sunday Temperatures warming back to the 50s early next week Leaning warmer and slightly wetter pattern continues in 8-14 day outlook (Nov 13-19) Historical Weather: Looking back at the November 6, 1990 snowstorm that brought up to 8.5 inches of snow and a record low of -1°F Recent Conditions: Six consecutive weeks of above-average temperatures ended with near-normal conditions at the end of October Western Iowa received a quarter of its monthly precipitation in just two days Fall foliage peaked with recent windy conditions Specialty Crop Impacts: Urgent: Harvest root crops (carrots, beets, radishes) before weekend freeze Protect lettuce with low tunnels; spinach and garlic can withstand cold Venting strategies for high and low tunnels to prevent moisture buildup and acclimate crops to cold Plant garlic now if you haven't already Tips on heating high tunnels for winter production Looking Ahead: The podcast moves to a monthly schedule for the winter with the next episode on Wednesday, December 3rd.

Historical Weather: On October 23, 1908, southwestern Iowa received significant early snowfall—up to 11 inches in Clarinda Current Frost Event: 57 of 160-200 weather stations recorded temperatures at or below 32°F this week, though not considered meteorologically "widespread" Weather Forecast: Stable pattern for next few days, then rain chances Sunday night through Tuesday (0.5-1+ inches expected across most of the state) Temperature Outlook: Warmer than normal for late October/early November; synoptic-scale flow patterns emerging Climate Prediction Center: Slight warm signal and near-normal precipitation for Oct 30-Nov 5; Iowa is in climatologically driest time of year Frost Timing Discussion: Average first 32°F freeze occurs early October in northern Iowa, mid-October in central Iowa, and late October in southern Iowa—this year's frost came slightly later than average Crop Updates: Time to harvest sweet potatoes after frost damage; garlic planting research shows August 30 plantings can yield better than traditional Halloween planting Winter Outlook: La Niña conditions suggest increased variability with potential for polar vortex outbreaks, especially in second half of January and February; Minnesota may see patterns similar to 2013-2014 winter Snowfall Predictions: Team made guesses for first 1-inch snowfall at Des Moines airport (average date: Nov 26-Dec 3) summary generated using claude.ai

Weather History & Current Conditions Historical note: In 1950, Des Moines saw a 14° temperature spike in 5 minutes during a thunderstorm, reaching 87° due to prefrontal warming Current forecast: Cold front Friday with showers/thunderstorms, then cooler temps - returning to seasonal averages (mid-60s highs, upper-40s lows) Frost Watch Only 5 Iowa stations have hit freezing so far (Elkader, Sioux Center at 31°, Stanley, Spencer and Mason City at 32°) No widespread frost or freeze expected through end of October Growers advised to protect tender crops like basil during low-40s temperatures Precipitation & Long-Range Outlook Southwestern Iowa received 3 inches of rain (nearly a month's worth) Winter outlook shows classic La Niña pattern: leaning cold in northwest Iowa, wet in eastern Iowa for December-February Warmth persisting through end of October with near-normal precipitation Specialty Crop Updates Root crop harvest underway Spinach showing Cladosporium (fungal disease) in high tunnels—venting recommended Resources shared: eGRO water testing guide, corn earworm management in cut flowers Upcoming Events Albert Lea Seed cover crop show next Friday in Ames High tunnel short course November 12th at Iowa Arboretum featuring Becca Rudebusch, Dan Sheild, Brian Krug, and Natalie Hoidal summary generted using claude.ai

This Day in Iowa Weather History: 1970 early season snowstorm brought 5.1 inches to Sioux City - their earliest 1+ inch accumulation on record Current Weather Forecast: Slight warm-up through the weekend with above-average temperatures Isolated chance of showers/thunderstorms overnight and late Saturday into Sunday No widespread frost expected through at least October 24th Climate Outlook: 8-14 day outlook: leaning warmer and slightly wetter October outlook: warmer with equal chances for precipitation La Niña Advisory issued - conditions present and expected to persist through December 2025-February 2026 La Niña typically means drier/warmer falls and potential for more winter cold air outbreaks Recent Weather Notes: Past week saw summer-like temperatures 12-16°F above normal Statewide average of 72°F (14.7°F above normal) Cold front October 5th brought localized heavy rain (1.5-2.5 inches in diagonal band from southwest to northeast Iowa) Specialty Crop Impacts: Fall warmth accelerating fall crop growth (lettuce, etc.) Extended season benefiting delayed summer plantings Discussion of rice growing in Minnesota and overwintering onion planting strategies Tips on managing fall-planted flowers to avoid early flowering Upcoming Events: High Tunnel Short Course - November 12th at Iowa Arboretum, Madrid, IA (registration now open) Topics: high tunnel peach production, transplant watering strategies, high tunnel soil health management Impact Squared Virtual Visioning Activity - November 6th, 6-7:30 PM Help inform climate tool development for small-scale and specialty crop farmers $100 Amazon gift card for participants Bonus Weather Fact: First EF5 tornado in over 12 years confirmed in North Dakota (June 2025) - last one was Moore, Oklahoma in May 2013 podcast summary generated using Claude.ai

Weather History & Forecast: 1942: Early snowfall hit Iowa on this date, with up to 4 inches accumulating in some areas Coming week: Unseasonably warm and dry with sunny days, temperatures above normal Extended outlook: Strong warm signal through early October, particularly in upper Midwest Recent Weather: Past week: 8-12 degrees above average statewide First above-average rainfall period in weeks (with the highest, 4.54", in Fort Dodge!) Eastern Iowa remained drier than western areas Specialty Crop Updates: Peppers: Good yields continuing due to warm weather; some cyclamen/broad mite issues observed in Newton area Carmen peppers: Unusual spiciness reported - growers advised to check Melons: Reduced solar radiation from cloudy, wet summer conditions may have contributed to poor season (theory posited by Jordan Lyon, Buser's Produce) Tomatoes: Splitting issues due to uneven rainfall patterns Frost Outlook: No widespread frost expected through October 11th based on dew point forecasts Warm, dry conditions may still allow nighttime cooling near normal levels Upcoming Events: October 4: Nut Growers of Iowa field day (Centerville/Ottumwa) October 7: Shimek Forestry field day (southeast Iowa) October 9: Yellow River Forestry field day (northeast Iowa) Greenhouse/High Tunnel Tip: Control weeds now to prevent pest and disease carryover through winter   Podcast Summary generated using claude.ai

• Historical Weather Moment: In 1912, Iowa experienced extreme weather swings from 104°F heat to snow flurries within just 9 days in September • Current Forecast: Unsettled weather with cut-off low pressure system bringing increased precipitation chances, potential storms with wind and small hail, but overall benign conditions • 8-14 Day Outlook: "Red bullseye" over Iowa and Minnesota indicating high likelihood of above-normal temperatures (mid-upper 70s vs normal) through September 30th • Recent Weather Events: Northern Iowa hit with 1+ inch hail reports across multiple counties; Fort Dodge area received 4+ inches of rainfall; most of central Iowa remained dry • Summer Glory Index Results: Iowa's meteorological summer rated as "fine" with SGI of 1420, held back primarily by July's high dew points and overnight lows; only 3 days reached 100°F in Western Iowa • Fall Foliage Prediction: Favorable conditions for vibrant fall colors with warm days, cool nights, and sunshine; early color changes already spotted on individual tree branches • Specialty Crop Update: Poor pumpkin harvest continues due to fruit set issues and rot problems; fall brassicas showing alternaria from earlier wet conditions but later plantings look strong; fall carrots performing well   Summary generated using Claude.ai

Weather Forecast & Climate Updates • Hot and dry conditions ahead with temperatures in low-mid 90s and heat index values in mid-upper 90s • 8-14 day outlook shows continued warmth into late September with slight chance for above normal precipitation • ENSO update: 71% chance of La Niña transition October-December, signaling potential warm and dry fall/winter This Week's Weather Recap • Chilly temperatures that felt great after a hot summer • Mostly dry conditions with under 0.4 inches for most of the state • First freeze of season recorded at Stanley, Iowa (32°F on September 7th) Specialty Crop Impacts • Pumpkins: Strong auction prices ($5-10 vs typical $2-3) but poor growing season with fruit set issues • Cucumbers: Cold damage causing unmarketable scarring at Featherstone Farm • Melons: Season ended 6+ weeks early, creating H-2A labor contract challenges for growers • Watermelons: Poor year especially in low-lying areas due to fruit rot • Flowers: Mixed reports - Rose Farm had great year, others experienced delays • Honey production: Drastically reduced to 1/5 of expected yields, indicating widespread pollinator issues Historical Weather Note • September 11, 1917: Earliest freeze on record hit eastern Iowa with temperatures as low as 30°F, causing considerable damage to corn, potatoes, and other late crops Coming Next Week • Summer Glory Index results and fall foliage outlook Podcast summary generated using Claude.ai

Weather History & Forecasts Iowa Weather History (1989): Large thunderstorms brought heavy rain to western Iowa with severe weather and brief tornadoes, causing wind damage, roof damage, and trees falling on cars 7-Day Forecast: Cool autumn weather with clear skies and below-average temperatures; best rain chances on days 4-6 due to Atlantic activity and shifted Bermuda high Climate Outlook: September 9-13 shows slightly warmer temperatures and higher precipitation chances in western Iowa; monthly outlook suggests equal temperature chances and wetter conditions statewide Weather Summary & Notable Events Past Week: Most of Iowa received below-normal rainfall (0.5" below average), except western/southwestern Iowa which saw above-average amounts Cold Snap: Some locations hit around 40°F, causing potential localized damage to sensitive plants like basil but not widespread frost damage Summer 2025 Overview: 10th wettest summer in 153 years with 18.5" total precipitation (5" above average); July was 2nd wettest on record; August was drier at 3.4" (0.75" below average) Heavy Dews Explanation Seasonal Pattern: Heavy dews occur in late August/early September due to shorter daylight hours and cooling surface temperatures Science: Earth radiates heat overnight while warm air masses remain overhead, reaching dew point and creating heavy condensation Crop Impact: Wet leaves from heavy dews can promote foliar pathogens and crop decline Specialty Crop Topics Foxtail Grass Seeds: Grower concerned about viability of mowed green foxtail; recommended germination testing with moist paper towel method Compost Management: While beneficial, compost can raise soil pH and create phosphorus excess due to 1:1:1 N-P-K ratio; rule of thumb: 1% organic matter = 20 lbs nitrogen per season Nitrogen in Rainfall: Addressed grower question about delayed flower blooming; rainfall contains minimal nitrogen (0.5-3 mg/L) compared to irrigation water nitrate levels (10+ mg/L); plant greening after rain is primarily due to improved nutrient availability from soil moisture, not atmospheric nitrogen Cover Crops: Good timing now for oats and peas establishment; winter rye timing approaching; recommend seeding when rainfall is expected Episode Summary created by Claude.ai

Weather Forecast & Conditions: Cold front moving south from Minnesota will stall over Iowa, bringing rain chances Friday-Sunday Expected rainfall: up to 1-1.5 inches in northwest Iowa, less than 0.5 inches elsewhere  Cool temperatures continuing into early September (50-60% chance of below normal temps) First overnight lows in the 40s recorded this past week Historical Weather Note: August 28, 1979: Violent F3-F4 tornado tracked 45 miles across southwestern Iowa, killing 2 people and causing millions in damage Growing Season Challenges: One grower called this "the worst growing season in recent memory" due to excessive rain and heat Watermelon season ending 1.5 months early due to persistent rainfall (14 inches over 2-3 weeks) Widespread crop diseases including Phytophthora on pumpkins, pepper anthracnose, bacterial spot, and southern rust on sweet corn Specialty Crop Impacts: Cut flower growers dealing with high soil pH (7.7) and nutrient leaching Recommendations to remove diseased peppers to prevent further spread Discussion of sprayer technology resources for disease management Looking Ahead: Hope for warm, dry fall to help struggling crops mature Next week will feature meteorological summer season review and in 2 weeks, the Summer Glory Index results Podcast summary generated using Claude.ai

What in the Weather? - August 21, 2025 Episode Summary Weather Discussion Historic perspective: August 21, 2004 saw unusually cool temps (upper 30s) in northern Iowa - opposite of current conditions Hot summer analysis: July averaged 2°F above normal with exceptional humidity (85% of days had above-average dew points) Heat index impact: Triple-digit heat index values driven more by high dew points (upper 70s-low 80s) than air temperatures Moisture source: Gulf moisture "gate wide open" with southerly winds bringing exceptional humidity to upper Midwest Forecast Weekend cooldown: Dramatic temperature drop to highs in 70s, overnight lows in upper 40s-mid 50s Extended outlook: Southeastern Iowa likely colder late August, September outlook shows warm/dry trend Precipitation: Minimal rainfall expected (0.1-0.25") with best chance Friday night into Saturday La Niña watch: Potential fall development could affect late October/November weather patterns Specialty Crop Impacts Disease issues: Rhizoctonia root rot affecting snapdragons; tomato brown rugose fruit virus causing uneven ripening Pest spotlight: European corn borer infesting dahlia stems and peppers - biological control with Trichogramma wasps recommended Growing challenges: Excessive moisture limiting planting windows; late-planted fall crops struggling to establish Crop performance: Good pepper year for some growers, but eggplant and tomato fruit set suffering from heat stress Resources Penn State cut flower production newsletter Utah State University cut flower resources

Coming in September to your favorite podcast platform: Pivot Points, a new podcast exploring the stories of farmers who have made big changes to their farms and in their lives. Follow the Pivot Points podcast to make sure you get the podcasts as soon as they are released.

Iowa's top 10 historical rainfalls • 10th Place: Sheridan (Lucas County) - 11.23 inches on August 27th, 1903 • 9th Place: Ionia (Chickasaw County) - 11.25 inches on August 9th, 2021 • 8th Place: Dumont (Butler County) - 11.28 inches on July 17th, 1968 • 7th Place: Castana Experimental Research Farm (Monona County) - 12.02 inches on July 17th, 1996 • 6th Place: Bonaparte (Van Buren County) - 12.1 inches on June 10th, 1905 • 5th Place: Hudson (Black Hawk County) - 12.28 inches on June 1st, 2000 • 4th Place: Rathbun Dam (Appanoose County) - 12.34 inches on August 24th, 2007 • 3rd Place: Le Mars (Plymouth County) - 12.41 inches on January 5th, 2009 • 2nd Place: Audubon - 12.53 inches on July 2nd, 1958 • 1st Place: Atlantic 1 NE (Cass County) - 13.18 inches on June 14th, 1998

Main Topic: "Corn Sweat" Phenomenon Definition & Media Coverage "Corn sweat" is simply a catchy term for evapotranspiration Justin Glisan was interviewed by major news outlets (Washington Post, CNN, USA Today, CBS) The phenomenon was trending during the hottest week of July 2025 during a heat dome Scientific Reality Corn releases water vapor and oxygen through transpiration (not actually "sweating") Adds 3-5% to relative humidity locally (3-5 degrees to dew point) Peak evapotranspiration occurs during corn pollination/tasseling season Iowa has 13 million acres of corn contributing to this effect Comparative Analysis Prairie grasses actually have slightly higher evapotranspiration rates than corn Corn and soybeans have very similar ET rates during peak growth Historical prairie landscape would have different hydrology and soil structure Modeling is used to understand these complex comparisons since full-scale experiments aren't feasible Weather Forecasting History First tornado warning issued in 1940s by Miller and Fawbush at Air Force base WWII and 1946 weather radar development improved forecasting capabilities 1925 Tri-State tornado killed ~700 people despite warning signs, but no communication system existed Modern forecasting balances accuracy with avoiding "boy who cried wolf" scenario Social Media & Public Education Madelynn Wuestenberg urges people to stop sharing corn sweat TikToks Working on program to fact-check weather-related social media content Emphasizes need for agricultural meteorologists with both meteorology and agronomy backgrounds Summary generated by Claude.ai

Historical Weather (This Day in History - 1993) Severe thunderstorms moved from Nebraska to western Iowa at 60 mph Wind gusts exceeded 70 mph, with 75 mph winds in Pottawattamie County destroying barns Council Bluffs received 2 inches of rain in 30 minutes causing urban flooding Des Moines recorded 83 mph wind gust 1993 was record wet year for Ames (20 inches of rain in July alone vs. 8 inches in July 2025) Current Weather Forecast Short-term (Justin Glisan) Rainfall chances continue through Friday night Cold front broke heat dome, bringing dew points down Temperatures: mid-80s through weekend, then back to 90s Minor rainfall chances early next week Northern Iowa has less rain chance as storm track moves south Expected rainfall: 3/4 inch statewide (below normal), 1.5-2 inches in southwestern Iowa Extended Outlook (Madelynn Wuestenberg) 6-10 day outlook (July 29-Aug 2): Slightly below normal temperatures in north, near normal in south; 33-40% chance above normal precipitation 8-14 day outlook (July 31-Aug 6): Continued slight chances of below normal temperatures; western Iowa slightly wetter, eastern Iowa near normal Normal temperatures: Daily highs mid-80s, lows in 60s Recent Weather Events Heat and Humidity Yesterday and prior day were hot, with cloud cover mitigating worst conditions in central Iowa Eastern Iowa experienced "dew point pooling" with dew points in upper 70s-low 80s Hottest reading: Dubuque Lock and Dam hit 95°F with heat index of 110°F Severe Weather 6 AM tornado warnings in central Iowa Tornado warnings near Maxwell and eastern Iowa Caused by remnants of mesoscale convective vortex from Kansas moving along warm boundary Rainfall Totals (Past 7 Days) Northeast Iowa: 4-4.5 inches (highest) Central Iowa: 3-3.5 inches Southwest Iowa: Trace to 0.25 inches (lowest, drought conditions persist) Specialty Crop Impacts Garlic Disease Investigation Farm in Chariton, Iowa had garlic crop with yellowing (suspected aster yellows) Testing revealed it was a virus, not aster yellows phytoplasma Cannot save seed for next year due to virus Comparison with aunt's clean stock showed dramatic difference At a different farm, possible Embellisia skin blotch observed on garlic wrappers Brassica Issues Black rot & alternaria affecting collards, broccoli, and kale Wet conditions exacerbating disease problems Nutritional Concerns Nitrogen leaching due to excessive moisture Fertilization may be necessary to supplement leached nutrients Crop Performance Issues Onions in Central Minnesota: Unexpectedly bolting across all varieties (planted from seed this spring) Zucchini: Poor fruit set, currently "worst crop of the year" candidate Tomatoes: Slow growth, fruit remaining green General pollination: Poor across multiple crops due to hot, wet conditions Heat may be affecting fruit set in tomatoes and peppers (flower abortion) Upcoming Events July 30: Cut flower field walk at River Root Farm (Decorah) July 31-Aug 1: Plant Peddler educator field day and variety day (Cresco) August 2: Grow Johnson County field day and food safety workshop August 5: Iowa State fruit and vegetable Field Day August 20: Midwest mechanical weed control field day Show Notes Hiatus announcement: No new episodes for 3 weeks (pre-recorded content only) Return date: August 21st, 2025 summary generated using Claude.ai

Weather History On July 17, 1972, slow-moving morning thunderstorms dropped 5.5 inches of rain at Sioux City, setting the all-time daily rainfall record there (still standing). Other highlights: 4.63 inches at Sac City, 3.45 inches at Humboldt. Short-Term Weather Outlook Cool air has returned after a recent frontal passage, but temperatures are forecast to increase again heading into next week. There are chances for showers and thunderstorms through the weekend. A "Ring of Fire" storm pattern will set up as a heat dome builds south over Missouri, leading to more storms along its northern edge (ridge riders/squall lines), likely north of Iowa, affecting the Upper Midwest (ND, SD, MN, WI). Medium-Range Weather Setup The bullseye of the heat dome appears over Missouri July 22–26; during this time, Iowa will see a precipitation gradient, with most rain favored in northeast Iowa. Precipitation forecast is variable, and storm placement will become clearer closer to each event. Southeast Iowa (and previously drier northern counties) have recently received significant rainfall, shifting them from "have-nots" to "haves." Ottumwa remains in moderate drought ("D1") as a stubborn dry spot. Climate Outlook 6–10 and 8–14 day forecasts show high probabilities for above-normal warmth (especially south), then continued wetness through late July. The 3–4 week outlook through August 8 gives no clear signal on temperatures, with a slight lean toward dryness in southwestern Iowa. Initial August outlooks show "equal chances" for temperature and precipitation over southern and central Iowa, a result of persistent widespread soil moisture which helps moderate heat. Atmospheric Impacts Recent wetness tamps down temperature extremes due to moist soils and increased cloud cover. The area's high dew points indicate low atmospheric demand, reducing drought risk but potentially increasing plant disease issues. Past Week's Weather Severe weather last Friday produced two weak tornadoes in southern and eastern Iowa, with no widespread damage. Wildfire smoke from Canada arrived over the weekend after a strong cold front and wind shift to northwesterly flow. Wet conditions continued across much of the state. Specialty Crop Impacts Foliar Disease Risk Prolonged wet conditions are increasing foliar disease risks in specialty crops. Preventive fungicide programs are recommended for conventional growers, especially on brassicas (cabbage, broccoli, cauliflower). Summary of biopesticide efficacy for brassica diseases (per Meg McGrath, Cornell University): For black rot: Oxidate worked in 1 of 1 trial, Regalia in 1 of 2, copper in 4 of 5, Double Nickel in 1 of 1. For alternaria: copper is most effective. Over-use of copper risks resistance and soil accumulation; organic certification requires soil copper testing before use. For basil downy mildew: Only resistant varieties (notably the Prospera series) provide reliable control—fungicides are not effective. For powdery mildew on pumpkins and squash: Use potassium bicarbonate products like Kaligreen or Milstop (these are safer than baking soda due to plant salt sensitivity). Disease and Cost Monitoring Meg McGrath's cost-per-acre chart helps growers compare costs of biopesticides and fungicides Beet and Swiss Chard Disease Cercospora leaf spot is appearing on beet and Swiss chard leaves, making chard unmarketable. Resistant varieties like Char Bell are advised for chard. Japanese Beetle Management Listener asked about Milky Spore for Japanese beetle grub control. Dan cautions little evidence supports its effectiveness and prefers pest exclusion over soil treatments, since beetles migrate from other areas. Pheromone traps may attract more beetles than they catch—sometimes best given to neighbors to ward beetles away from your crops. Colorado Potato Beetle Resistance The second generation of Colorado potato beetle larvae has emerged. Rotate insecticide chemistries to avoid resistance (e.g., use Azera in the second generation if spinosad was used in the first). Non-chemical methods, like knocking beetles into a soapy water bucket, remain effective—plants tolerate up to ~33% defoliation before yield loss. Announcements and Events The Fruit and Vegetable Field Day at Iowa State University's Horticulture Research Station will be held August 5th, 2:00–5:30 PM (free, with supper and registration link provided). The Plant Peddler "Educate the Educators" Day is July 31st in Cresco, with a feast and entertainment; the next day is Variety Day showcasing mature bedding plants (trade show only, not for sale). Practical Farmers of Iowa opened applications for the horticulture program coordinator position. Podcast summary generated using perplexity.ai

Recent Iowa Weather Highlights Heavy Rainfall: Rain gauges in the Des Moines area report 1–2.2 inches; some areas in western/central Iowa received up to 6 inches in the past week. Southeast Iowa remains much drier, with some locations getting less than 0.1 inch.   Historical Context: July 11, 1993: Major flooding in Des Moines, with 250,000 residents losing water after levee breaches. 1993 marked 20 out of 37 consecutive days of measurable rain somewhere in Iowa. Current Wet Stretch: Statewide rainfall is 137% of normal for July so far. Several stations have received half a month's rainfall in just the last 10 days. Dew points remain high (60s–70s), signaling ongoing Gulf moisture. Weather Outlook Short-Term Forecast: Active weather continues for the next two days, with a chance of severe storms (supercells transitioning to linear systems). Flood warnings and flash flood watches remain in effect. After the weekend, temperatures return to the 90s, then cool down. Medium & Long-Term Outlook: July 16–20: Likely below-normal temperatures, leaning wet. July 18–24: Continued cool and wet trend. End of July: Warmer temperatures expected, with equal chances for precipitation. Southeast Iowa may remain drier than other regions. Regional Details: The "blue bullseye" for cooler weather covers eastern Nebraska, most of Iowa, Minnesota, and Wisconsin. Weather Patterns & Impacts Storm Dynamics: Stationary fronts and ample Gulf moisture are causing repeated thunderstorms. Linear wind profiles have led to more squall lines and fewer tornadoes. "Training" thunderstorms have produced localized heavy rain. Precipitation Trends: 40% of Iowa's annual precipitation typically falls on just 10 days. High-intensity, short-duration rain events are becoming more common, often leading to localized flooding and drought in different parts of the state. National Weather Note: Texas Flooding Recent Event: Two Texas locations received 11 inches of rain in just over 24 hours. Catastrophic flooding on the Guadalupe River, with water rising 20–30 feet in under an hour. Factors: Gulf and monsoonal moisture, remnants of Tropical Storm Barry, and stalled weather systems. Similar patterns have caused flash flooding in Iowa (e.g., Clive in 2018, Des Moines metro in 2019). Specialty Crop & Pest Updates Disease Risks: Continued wetness raises concerns about foliar diseases (e.g., black rot in brassicas and cabbage). Wet conditions and heavy dews may increase disease pressure as the season progresses. Pest Observations & Management: Japanese Beetles: Active on crops like zinnias, basil, and sweet corn (can affect pollination if silk is heavily clipped). Control options: Conventional sprays (e.g., Mustang Maxx), manual removal, and using trap crops. Colorado Potato Beetle: Reports of spinosad resistance. Alternative controls: Physical removal (bucket method), azadirachtin, or biological products (though some, like certain BT strains, are hard to find). Potatoes can tolerate 33% defoliation before yield loss. Onion Thrips: High populations observed in some fields, causing silvery-white damage. Economic thresholds vary (1–3 thrips/leaf per Cornell/UMass; up to 30 per UC). Control: Multiple modes of action, increased spray volume, horticultural oils, azadirachtin, and soil treatments with fungi or nematodes. Other Notes & Events Field Days & Workshops: August 2: Field day at Grow Johnson County's Poor Farm, covering no-till vegetable research and a short food safety workshop (counts as an annual update for PSA-trained growers). Agrivoltaic field days in Ames: Ongoing research on crops grown under solar panels, with field days every other week through September. Podcast summary generated using perplexity.ai