The +40C vs -40C discussion is often misleading. -40C is exceedingly rare in Edmonton. There are not many days where it gets to that in say Edmonton region.
I counted 46 instances of -40C or lower in last 25yrs. Thats less than 2X per year. We tend to forget how rare that is when we're in the middle of a cold snap. For instance 11 of those 25 yrs we didn't hit it at any point in the year.
Chart and data: Number of Days with a Windchill ≤ -40 - Annual data (25 years) for Edmonton for Edmonton, Alberta, Canada
edmonton.weatherstats.ca
Contrast the places like Phoenix Arizona that are hell of +40C temperatures. Phoenix last year had 31 days in a row where the high did not get under 43C. These are heat lethal days. 31 in a row.
The total for Phoenix is worse, far worse. 55days this year where it was +110F or higher. (+43.3C)
So that Phoenix saw the absurdly high spikes in temp 55 times in one year. Which is more than the -40C days we've seen in the last 25yrs.
So that its fine to discuss the hypothetical likes. But the actual temps in Edmonton vs some US desert cities is quite a different matter. We have an astoundingly more temperate climate, and easier to live in.
Nor is Phoenix enjoyable at night during heat waves. Quite often now temps overnight in Phoenix area can hover in high 30's. So that basically Phoenix see's little reprieve ANYTIME during heat waves.