When Sonnet 97 spoke of an absence from his lover that felt to Shakespeare "like a winter" even though it actually took place during the summer and/or autumn, Sonnet 98 speaks of either the same or a similar absence that took place during the springtime in April, which, however, on account of not having his lover around, to Shakespeare also seemed like "winter still." 

With their many similarities and essentially identical themes, the two sonnets are clearly related, and it is unlikely to be a coincidence that they follow each other in the collection, although we cannot know whether our poet is here talking about a continuous absence from his lover that lasts all the way from late summer into the next spring, or whether he is talking about a renewed period of separation, or whether in fact the two sonnets have somehow got reversed in their order and we are looking at an absence that lasts from spring throughout the summer into the autumn.

This latter scenario seems an unlikely one, as we discussed when looking at Sonnet 97, and so indeed do various other theories which see both these sonnets as merely emotional but not physical periods of separation, or as either referring to periods of separation from two different people, something we also saw and noted in the last episode.