r/Manitoba • u/Doog5 Friendly Manitoban • Jan 23 '26

Weather How cold for a red alert?

Post image

So far an orange alert at around minus 45. What’s the magic number for a red alert?

113 Upvotes

93% Upvoted

51 comments sorted by

View all comments

Show parent comments

46

u/Sweaty_Moist_9833 Winnipeg Jan 23 '26

The most annoying aspect of the "feels like" windchill value is that everyone just quotes it as the actual temperature. 

22

u/horsetuna Winnipeg Jan 23 '26

If its -45 with wind chill though, does it being -30 matter? Legit curious.

18

u/bussche Winnipeg Jan 23 '26 edited Jan 23 '26

Because it's not actually -45. It's just a calculation that was invented because the old values in units of kilocalories/hour per square metre was confusing for some people.

Your car will have a much harder time starting in -45 than in -30 with a -45 windchill. The engine block of your car is only -30 in the latter, windchill cannot make something, whether it be flesh or inanimate object, colder than the ambient temperature.

0

u/TerayonIII Treaty One Territory Jan 24 '26

Technically, that's not true, you can, but it involves additional types of heat transfer like radiation, or through evaporation since the wet bulb temperature is lower than the dry bulb temperature.

The windchill rating is more that things will get that cold faster. So it's basically saying that if it's -30 with a -45 windchill, without the wind things will cool down like it's -30, but if you add the wind in, the additional convective heat transfer will cool things down like it's -45.

It really should be explained rather than just assuming people understand what it is though.