Snow or rain a big NO! I won't ride in the dark either just to risky. Cold is a maybe. I'm trying to push myself to ride when it is 45 F or above - a new low temp threshold for me this season. I hate to be cold and my hands and feet just do not handle it well (had mild frostbite in college). I've tried the hand warmers/toe warmers. They keep my hands warm but do nothing for my feet. I'm going to try and ride tomorrow - high is forecast to be 48 F - all I can do is try. If I don't ride outside I'll give the fluid trainer a good work out for an hour or so. Either way I'll ride.