Well, I live in michigan and it's already pretty cold here. I would wait until it's nice and sunny outisde to do the resin/fiberglass work if you don't have a garage to work in. You normally want it pretty warm outside so that it properly cure's. However, some people have even made a heat box so that they can still work on their stuff even in the cold.
I am having to wait until about April to do the resining on my stuff. Until then, I am just working on the paper part.