Moderator Note
Let’s avoid the snark in GQ. No warnings issued.
Colibri
General Questions Moderator
Haven’t read everything. Just popped in to tell an anecdote. At a school where I worked there was a case of hypothermia that happened in 30°C heat on a sunny day. A 14 year old girl attending sports training suddenly had her core temperature plummet. It took a while to work out what was happening.
It turns out that there were additional factors – she hadn’t eaten that day, she was borderline anorexic, she had just done some strenuous exercise and had been sweating, the wind had risen for a bit causing her to chill. She just didn’t have enough fuel in the machine to keep her own body temperature up.
So, in answer to the OP, I would have to say pretty much any temperature would render hypothermia a possibility – after all it is defined as a drop in core body temperature which is not always directly related to ambient temperature.
OTOH, I wouldn’t normally consider it a significant risk factor until it was at least below 10°C – for a group of healthy, dressed adults in low wind conditions.
The presence of sunshine and the absence of wind can make 35F feel very comfortable in shirtsleeves. I’ve gotten out of my car on a sunny, calm afternoon in the 30s with snow on the ground, and in 15 or 20 minutes, still felt no need to grab for a jacket.
I once read (sorry, no quote) that Australians would sleep in the nude (or nearly) when the temperature fell to as low as 40F. I assume that they were adapted to it, maybe they had lots of beige fat, whose creation is enhanced by low temperatures. I just read about this in American Scientist: http://www.americanscientist.org/issues/feature/2014/4/can-skinny-fat-beat-obesity, which is, unfortunately, behind a paywall. But you can read the abstract.
Just an experience:
Ft Carson, CO.
Winter of 61/62
Basic training.
Week in the field, pup tents, no hot food or drink at all. Everybody felt like they were freezing.
Regular training so we were active a lot through the day.
By the third day, liners were out of the field jackets, ear flaps up, one pair of socks worn, glove liners out, not wearing gloves.
Soon jackets were totally unbuttoned and no one was complaining about the cold.
I am naturally a heat engine & the wife is always cold. ( This is caused by marriage I think. )
I sit in 60° still room and work hard math problems which needs much concentration and a heat zone builds around me to the point I start sweating. On the flip side, at 68°, I must have air movement to be able to sleep without sweating.
I can stand very hot work conditions with sufficient air movement & water and I need more as I grow older. 5 of my 7 siblings are the same. 2 are more or less normal in this regard.
I seem to find many people that are on both ends of the spectrum & not average.
I would image this is in the arid/semi-arid areas, where the humidity if very low?
Not moving around a lot? I’d guess like 50, 55 farenheit. Maybe as low as 45. Depends on the size and fat of the person
if the person can run around to keep his temp up, it’s a whole different story.