210 wind chills — what temperature and wind add up to
A wind chill for every meeting of 21 temperatures and 10 wind speeds. At −10 °C with a 30 km/h wind, it feels like about −20 °C.
Find it by temperature and wind
By Environment Canada’s scale, exposed skin can freeze in 30 minutes below −28, in 10 below −38 and in 2 below −48. Clothing, damp and wind gusts shift those numbers a lot.
The air did not actually get colder
Wind chill translates how fast moving air strips heat from skin into a temperature. If the air is −10 °C, water still freezes at −10 °C no matter that it feels like −20 — and so do pipes, radiators and everything else that is not a person.
The first breeze does the most
Going from 5 to 20 km/h drops the felt temperature sharply; going from 40 to 50 barely moves it. The 0.16 exponent in the formula is what bends the curve that way.
How long bare skin lasts
By Environment Canada’s scale, exposed skin can freeze in 30 minutes below −28, in 10 below −38 and in 2 below −48. Clothing, damp and wind gusts shift those numbers a lot. (68/210)
The formula stops at 10 °C
It is defined only for air at 10 °C or below with wind of at least 4.8 km/h. Above that, wind cools you off rather than punishing you, so summer uses a different index entirely.
How to read this
- Feels like = 13.12 + 0.6215T − 11.37V^0.16 + 0.3965T·V^0.16, with T in °C and V in km/h.
- Stronger wind always lowers the number, but each extra km/h lowers it less than the last.
- The formula applies only at 10 °C or below with wind of at least 4.8 km/h.
- It is a measure of how cold a person feels, not of the air — water still freezes at the air temperature.
These are estimates. The standard formula assumes dry skin, shade and level ground: sunshine makes it feel warmer, wet clothing far colder, and what you wear matters as much as the number.
Frequently asked questions
Q. If it feels like −20, does water freeze at −20?
No. Water follows the air temperature. Wind chill converts how fast wind strips heat from skin into a temperature, so it applies to people only.
Q. Does twice the wind mean twice the chill?
No. The 0.16 exponent means the first breeze does most of the work; once the wind is already strong, more of it changes little.
Q. Does the number hold in bright sun?
The standard formula assumes shade. In strong sunshine it typically feels a few degrees warmer than the table says.
Q. Why does the table stop at 10 °C?
Because the formula is defined only up to there. In warmer air wind cools you off, so summer uses the heat index instead.
Q. Does dressing warmly change the value?
Not the value itself — it is defined for bare skin. Clothing is what stands between you and that number.