The coldest I can remember seeing in Stanley was -48, the coldest I have ever seen was -58 in Thule, Greenland. I have often heard folks say that once it is -20 after that it doesn't make any difference - having been exposed to temps well below that I respectfully beg to disagree with them.
drover
Asked my friend where he got that temp info I referenced in my original post, and he said it was from the station at the forest service office. Totally agree with you on the 'doesn't make any difference'. Tis Nonsense. I did a solo winter backpack trip behind Redfish lake last Xmas(2015) and saw temps of -30 at night with around -10 during the afternoon? That 20 degree diff. was very noticeable!
The people who say there's "no difference" between -20 and colder temperatures are 1) ignorant of real cold and 2) fools. Anyone who had had to work/live in truly cold locations knows there is a very real difference between -20 and -40; and -50 is ten times colder than -40; and -60 is so cold it defies description. At -40 you can function with a moderate amount of warm clothing; at -50, a 10 mph breeze will cut through a winter grade down jacket like a knife; at -60, you need leather and fur to survive prolonged time outdoors.
Metal fatigue at such temps can be critical. At -60 a crescent wrench will snap off as you try to loosen a nut on a bolt, and the valve on the top of a 100-pound propane canister will break right off if you tap it with a ball-peen hammer. I've had the first thing happen personally, and I saw the second happen from close enough to witness it, and far enough away I wasn't killed or badly burned like the other guys were.
"I'm gonna have to science the schit out of this." Mark Watney, Sol 59, Mars
