Many years ago i used to take two weeks leave and wander up to my uncles farm just outside of Marinette, Wisconsin. I would drive up before season, and we would start deer camp early by getting up early to see what travel patterns and places that the deer frequented early in their day as the sun was coming up and shooting time arrived. One year the weather was frigid, like we have been having the last week with temperatures dropping well below zero. I had scouted out a heavily used deer trail and found a nice Oak tree that was easy to climb and had a sturdy limb to stand on and a couple of others to cradle my butt and stabilize my position up in the tree. I knew that there was a nice eight point buck that frequented the area and found his tracks following the trail in fresh fallen snow. One morning we woke up to find the thermometer outside the window showing -20 degrees with no wind. Everyone else decided to go back to bed but I had thoughts of that buck wandering under my tree. I bundled up so that I resembled the Michelin Man, stuffed hand warmers my gloves and pockets and headed for my tree. I climbed up and stood on my branch, which by the way was eight inches in diameter and sturdy as could be, nestled my butt between the other branches and settled in watching and waiting for my buck to come wandering by. It soon became apparent that despite the heavy clothing and hand warmers time in the tree as well as out in the cold was going to be limited. I was giving some thought about climbing back down and heading in to warm up when there was a loud crack and I suddenly found myself laying in the snow, underneath the tree, the branch I had been standing on laying beside me, my rifle laying about ten feet away trying to catch the breath that had been knocked out of me due to the fall. Once I was breathing regular again, and freezing my butt off I tried moving arms and legs. I was lucky and somehow managed to still have everything working as intended. I picked myself up, gathered my rifle, which now had a cracked stock, and wandered back to the farmhouse. My uncle heard of my rapid excursion from up in the tree to the ground and explained that in temperatures that cold the wood would become brittle and often branches would fall off the tree with the slightest breeze, not to mention due to a 140 pound blonde standing on it. Later that morning I drove into town and dropped my rifle off at the local gunsmith's to get the stock repaired, which ended up getting replaced, and bought a new Winchester Model 70 in 30-06.
That was the last time I ever climbed up a tree during hunting season, and even after tree stands became popular still avoided any raised elevations.
To this day, when teaching Hunter Safety during the training on hunting from tree stands, I always advise the students not to use tree stands or climb up off the ground. I usually relate this story to them and explain how lucky I was not to be injured in the fall, but what might have happened if I had been knocked unconscious and laid out there and froze to death.