First: is there actually a mod out there which changes the seasons (mainly making the foliage on the trees change)? I have looked but can't find out.

Second: if there isn't could someone point me in the direction of mods like "summer in Skyrim".

It's a permanent change which would last the whole year round but I thought if I found enough of them I could simply swap them around when my in-game time reach the appropriate point.
It doesn't necessarily have to be anything fancy and I know the snowy regions of Skyrim will remain snowy all year round.

Would switching these around cause any problems in my game? I wouldn't imagine so because it's graphical but I'm a major newb.