I have a board friend who had the season get messed up in a similar way Skoobykat moved the family out of a lot, put the empty lot in the lot bin and placed it in another hood. In the new hood, the indicator said it was summer and the trees agreed, but the snow on the ground wouldn't go away and the sims were overheating making snowmen.
Were the community lots owned or unowned? Had you moved them at all? For what it's worth Maxis know something is buggy about owned business lots.
MaxoidSam says
"Q: Do the seasons not change on Community Lots?
A: They do not. This is by design, as Sims do not age on Community Lots, the Seasons will similarly not progress. However, we have discovered a BUG that the season on Owned Community Lots is actually getting stuck on the season it was on the first time the player saves on that Lot, and never moves forward. This is not the correct behavior. The Owned Community Lot should be in the same season that the player was in when they last left their home lot every time they visit that Owned Community Lot. This will be addressed in a Seasons Patch."
http://bbs.thesims2.ea.com/community/bbs/messages.php?threadID=c474bab6c4715412b6c71f4ce7784a0c&directoryID=148&startRow=1&openItemID=item.148,root.1,item.43,item.104,item.41,item.127,item.23