Each of Assassin's Creed Shadows' four seasons features different kinds of weather, but that won't affect gameplay because Ubisoft doesn't want it to have a "negative impact"
The different seasons in Assassin's Creed Shadows offer different weather effects - but you shouldn't worry about them affecting your gameplay. In an interview with Play magazine, Assassin's Creed Shadows art director Thierry Dansereau explains that Ubisoft didn't want the changing of the seasons "to be something that could be perceived as very negative or have a negative impact on how you play.