While deer hunting in the far north of Minnesota one year, we got some heavy freezing rain. I have a Model 70 and typically when I'm traveling to/from my stand I put the three position safety in "bolt lock and safe" position. I've carried in the position of "safe only", but occasionaly, going through brush and trees, I've had the bolt get kicked open and eject a good round. We can argue about this all we want, but that's not the point of my post.
When I got back to my vehicle, the freezing rain hitting my gun had frozen the safety selector lever. I could not get it to move. Thus, I could not unload the chamber as the bolt was locked. I sat in the vehicle with the heater on and the barrel pointed towards the passenger window (no one was in the passenger seat). Eventually, after about 20 minutes, the safety lever unfroze and I was able to cycle to bolt to empty the chamber. Now, anytime we get precipitation, I move the safety to the "safe only" position and am very careful about how I carry the rifle to ensure the bolt doesn't get kicked open in the brush.