I started playing A New Home on hard difficulty when the game was still at 1.0.0. When I saved my game, the temp drop schedule showed a three-level drop coming up in about a day and six hours and a two-level rise a couple of days later. I then loaded the save at 1.0.1. When the last batch of refugees arrived after a few hours game time, the temp suddenly dropped by one level. This was at 3 AM game time which is already a weird time for the temp to drop. Then I checked the temp drop schedule and it changed to an upcoming two-level drop followed by one-level rise two days later.

The weather forecast changes the moment the last refugee group gets in potentially subjecting you to significant temperature drops with no warning.

This is usually because you triggered the Winterhome event earlier than the game expected you to, and it has to "resync" the weather schedule in the lead-up to the game's finale.