It's worth mentioning this, because (A) it can happen to you, and (B) it happened to me last week.
Hypothermia is a very real concern in hunting: you're likely to spend hours sitting in one place or moving slowly, in all kinds of weather. It's easy to get cold - it kind of goes with the territory. The trick is learning when "cold" has moved to "dangerously cold", and there's no easy answer.
Here's what happened to me:
I went out for an afternoon, getting on stand just before 1:00, and intending to stay all afternoon - until about 4:45 when legal shooting light ended. It was chilly - in the low 40's - with a steadyish breeze. The weatherman was calling for showers, but it had been just overcast.
I sat in the stand and watched the world go by, flexing fingers and wriggling toes to stay warm as best I could. The afternoon dragged on, a tiny doe went by (at perhaps ten yards; I drew my pistol and had her lined up with my finger on the trigger before deciding she was too small), and the afternoon continued. It started to mist a little, and I shivered a few times as I sat there.
Eventually I decided that it was not a good day to hunt, even with 20-30 minutes of legal shooting light left. The mist had turned into a light drizzle and the wind had continued to blow. I was cold, damp, and pretty miserable.
I made my way down the ladder and plodded the quarter-mile back to the truck, set down my hat and gloves, and tried to unload my shotgun. Tried.
The Mossberg 500 has a catch in the shell feed opening that allows you to eject the shells one at a time without cycling them through the action. It's not hard to operate once you know where it is - just push "out" and catch each shell as it slides out. I couldn't get it to work for me, so I ended up cycling the slide and ejecting the shells into my hat.
Then I tried to get my coat off. I knew I was cold, but it was when I couldn't make the zipper on my coat work that I realized just how dangerously cold I was. I finally got out of my coat, tossed my gear in the back seat of the truck, and sat up front with the heater running for the next ten or fifteen minutes.
My only early warning sign was that bit of shivering (that I ignored). I'm used to being chilly while hunting: no matter how many layers you put on, sitting still in the cold wind leads to a chilly hunter. This went beyond chilly to true hypothermia. The difference on this particular day was the precipitation and the humidity. Overcast and windy isn't unusual around here, but the weather was, simply put,
damp.
It's easy to stay warm when you're dry. As soon as you get damp or wet, things can go downhill in a hurry.
I related this incident to my father a few nights ago, and he remembered his army days: stationed in Alaska, where temps were well below zero, he was never miserably cold. Walking post in Georgia at 38F and raining? That was the most bone-chilling cold he's ever experienced.
Take care of yourself out there, kids.