In the previous version, weather was randomly determined at the start of every player turn in November, and at the start of every player turn of April... but once it switched to mud or dry (respectively), it stayed that way until the following April or November. In other words, once the season turned, it stayed that way for months for both players.
Now it seems that the weather can flip-flop dry/wet/dry/wet in the same season. So if my weather rolls are bad and yours are good, you'll be campaigning in clear and I'll be campaigning over the same ground in mud, then it might dry up for you and start raining again on me. (Old grognards might be reminded of a similar screwy effect of random weather in the old Cobra.) This added dose of chaos will have a significant impact. I won't pass judgment until I get a chance to play, but it sure doesn't sit right.