The weather doesn't prevent me from prospecting in most cases. I have been out in the rain, snow, and even blizzards. I am more careful in new areas because I don't know how reliable the Forest Service roads are. We have had quite a bit of flash flooding in the past few months, and I don't want to get stranded.
I don't do much rock hounding in the winter because the rocks get frozen into the ground. Gold panning is different. If the river is flowing and I have enough water running through my sluice, it's all good. I dig the gravel from the river bottom instead of the shore.