Hey InvaderX. The timing system that wretchedshark proposed is a must before trying to do any other season-based systems. I'd suggest figuring out a scale; like every so many minutes in-game equals a day or whatever.
For season effects, there might be some opengl effects that could be useful for creating lighting; or maybe have some different sprites, like leafless trees for autumn.
Sounds cool, btw; I've been jotting notes and brainstorming with a buddy over a survival game inspired by Les Stroud. :)