Originally posted by Veseljko:

Weather is not random at all. Google for valheim weather calculator. You just need to enter your current world day and you will see all weather related data per biome including wind direction and speed, sunrise and sunset time, etc.
According to this calculator, weather is the same in all seeds.

Well this is very different to the last time I saw it being discussed. I notice though it doesn't have fog, only rain/storm/clear/blizzard.