RodeoMan Loc: St Joseph, Missouri

At minus 40 degrees below Zero, Fahrenheit and Centigrade are the same. In other words -40F = -40 C.

scoundrel Loc: Wytheville VA

You didn't say whether that was deg F or C, but it doesn't make much difference at that temperature anyway because it is so close to the crossover point of -40 degrees, where the number is the same whether reported in deg F or C.

Having spent most of my life in coastal California where snow or icy roads are front page news, I had to go to the mountains, or at least the foothills, for snow. On the other hand, triple-digit (Fahrenheit) temperatures were not that uncommon in the Central Valley during the summer. That changed a few years ago when I moved to Virginia and I encountered my first white Christmas in my memory, and I was a couple of years past traditional retirement age then. That was the year I met my first and lowest measured outside temperature of 14 deg F, but I was inside the house at the time. That Christmas was also the first and only time (so far) that I couldn't get into my car because the trunk and doors were frozen shut.

Cbrummer Loc: Lower Michigan

Northern Montana I think in the late seventies with more than a month below zero—cumulative chill

robertjerl Loc: Corona, California

During my two years stationed in sight of the beach in Vietnam, we had a couple of spells where the nights dropped into the 60s for a day or two. You would have thought it was Antarctica in winter from the reactions of the locals and guys who had been there long enough to acclimate.

Wyantry Loc: SW Colorado

Minus 40 degrees [still air temperature] Celsius & Fahrenheit (that is where they are both the same).

On the Sukunka River in British Columbia, Canada.

Dawson Creek —> Chetwynd, South on 29 to turnoff to road along the Sukunka River, past Sukunka Falls.

Bitter cold! Had to have engine oil heaters or run synthetic oil. Or both. Definitely battery heaters.

MT Shooter Loc: Montana

Endure? -51⁰ back in 1983. Today? -40⁰ at sunrise. Tomorrow? Supposed to be about the same!

dustie Loc: Nose to the grindstone

Add blowing snow, that has not crusted on top to keep it in place, and that's another added level of hardship to endure. For those who have not experienced the encounter, it's probably difficult to imagine the stinging, stabbing sensation of delicate little snowflakes being driven into contact with cheeks, lips, nose, eyelids, the edge of an ear that has peeked out from under protective cover...any skin parts that are not inside cover.
Under 12-15 mph wind and above 12°F to 15°F temp, it's not too dramatic, but over those wind speeds and below those temps, it's possible to wonder, sometimes, if all the skin layers are going to be abraided away.

Consecutive days and weeks of working in those environments can lead to an odd sensation of somehow being an element of the environment, distinct from and separated from associations with human comforts, like the body and mind have been taken through a transparent divider, into a nearby but dissimilar dimension. Maybe that is a different level or realm of consciousness that prevents the effects of the ambient environment from driving the mind into functional insanity.

dustie Loc: Nose to the grindstone

If reading and reminiscing on the rigors associated with deep cold has made some less than comfortable, maybe reading "The Cremation of Sam McGee" by Robert Service can restore some warmth and a smile.
https://www.poetryfoundation.org/poems/45081/the-cremation-of-sam-mcgee

Plieku69 Loc: The Gopher State, south end

ELNikkor

Jakarta, January 1995. Early one morning, security guards all bundled up, stomping their numb feet; it was 70 degrees F...

JeffL Loc: New Jersey

Eielson AFB, Fairbanks, AK, 1962: -65 actual temp!

joehel2 Loc: Cherry Hill, NJ

-30f in Lapland in February but thankfully it was a very still morning, no wind.

Ernie1945 Loc: Oxford, Ohio

The Winter of 1970. Fort Greely, Alaska. Field exercises with the US Army based out of Fort Wainwright, AK. Temperature reached -60 degrees (add wind on top of it). The TV station in Fairbanks sent a crew down to cover the exercises. They couldn't film it because the lubricant within their cameras became so thick that they wouldn't function. Along with sleeping in a tent at -20, that was it. Never complained about being cold again.

Nosaj Loc: Sarasota, Florida

-54, including slight wind chill, in Hill, NH., around 1977.

Wyantry Loc: SW Colorado

AND we are all waiting for someone who has been to McMurdo Station to check in . . . .