I have to agree with Cayugad. Before I would go about changing a bunch of things I may chaulk it up as just a bad day on the range.

Now if you never shoot in the cold and snow it may be a good idea to get out there a few more times and see if you have the same results. Also keep track of just your first shot as well to see how the cold is going to affect your most important shot a cold day with that nice buck in your sights. You know what I mean? A clean gun, cold powder and bullet cold. I know I need to do this more.