Ok, minor spoilers ahead:
The game takes place in June in the early 90's. Obviousl, New Orleans is sweltering heat, for anyone that has visited the southern US during that time. However, when Gabriel flies to Germany and goes to the fictional town of Rittersburg, it's snowing, and the amount of snow around looks as if it has been snowing for quite some time.
Now, I've lived in Germany, and every summer was extremely hot and muggy, and I lived in Southwest Germany. Did anyone else find this strange? I know the alps can have extreme weather, but I highly doubt Rittersburg was meant to be there.

I think it was more a style choice. The idea of a castle in the mountains surrounded by snow is a very romantic ideal that's quite prevalent in how people, especially in the west, think of them.
It may not be 100% accurate, but it makes for a much better story. Especially when contrasting the exterior cold to the interior warmth of a centuries old castle homestead.

This is actually mentioned in-game. The girl you meet in the castle talks about it if you use the ! dialogue option (instead of the ? option).