The coldest temperature I ever experienced for a prolonged period was -26 degrees F, which is about -32 degrees C. It was during our flintlock deer season in January. It wasn't bad because I was dressed for it and the wind wasn't howling. But deer guts never felt so good when I finally shot a doe. That was before I would think to use any kind of handwarmer.
On the other hand, I got hypothermia on a last day of flintlock season some years ago when the weather turned abruptly colder. I hit a deer just as the wind began picking up, and it took off into a myriad of other tracks in the snow. I rushed to track it because the snow began blowing and drifting, and threatened to obscure the trail. I followed it for a long way a at a very fast pace and began perspiring. I ended up losing that deer because the tracks became impossible to follow, and I still feel terrible about it to this day. I was now a couple miles from my car, and had to hike back into a severe headwind with heavy blowing snow.
What had started off as a +25 degree F day turned into a howling blizzard, but I don't think it ever got much colder than +15 degrees F. Wind chills were certainly below zero F though. Visibility dropped to near zero and I had difficulty finding my car as I was shivering uncontrollably in my damp hunting clothes. I resisted the urge to drop my gun which was very hard to grasp, or to just lay down and curl into a ball. By the time I got there, my thumbs and fingers weren't working well at all, and it took about 10 minutes to retrieve my keys from my pocket and open the door locks. I kept dropping the keys and just couldn't get the key into the lock. Then it was another several minutes to get the key into the ignition and run the glow plugs a couple times to start the diesel engine. This car had a good heater once you began driving it, but threw virtually no heat until it was running under load. I wasn't about to get out again to scrape the ice off of the windows, so had to drive for several miles with the side window down so I could almost see where I was going. I was still frozen and shivering when I got home 45 minutes later, and had to thaw out in a hot bathtub.
I learned that there is more to enjoying extreme winter weather than just the outdoor temperature and the amount or type of clothes you are wearing. Many of the newer insulating fills and fabrics such as Thermax, polypropylene, polyester fleece, etc. make sitting on a below zero deer stand much more enjoyable than the hand-me-down hunting clothes my Dad had me wear when I was a kid. I did however really miss the size 10 Mickey Mouse boots that I outgrew when I was in 8th grade. Korean war vintage Hood's or Bristolite's are much better than the later air valve type.
