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Weather

Wind chill calculator

Enter the air temperature and the wind speed: the wind chill shows, in °F and °C, with the risk level published by Environment Canada.

°F
mph

Wind measured at 10 m (33 ft), as in weather reports.

Wind chill

-19°F

That is -29 °C.

Risk level (Environment Canada)

High risk

Exposed skin can freeze in 10 to 30 minutes. Check your face and extremities for numbness or whiteness.

Quick challenge

Streak 0Best 0

Test yourself: every answer is computed by the tool, and the wrong choices are the most common traps.

How it works

Formula: WC = 35.74 + 0.6215T − 35.75V^0.16 + 0.4275TV^0.16

Wind chill expresses how cold the skin feels when the wind blows. The US National Weather Service formula is wind chill (°F) = 35.74 + 0.6215T − 35.75V^0.16 + 0.4275TV^0.16, with T in °F and V in mph, defined at or below 50 °F with winds above 3 mph. Environment Canada uses the same index in °C and km/h, wind measured at 10 m, plus a second formula for winds under 5 km/h.

Worked examples

  • 0 °F with a 15 mph wind

    Wind chill of -19 °F, the National Weather Service's own example.

  • 10 °F with a 30 mph wind

    Wind chill of -12 °F.

  • 25 °F with a 2 mph breeze

    23 °F, with Environment Canada's low-wind formula.

Common mistakes

  • Thinking wind cools objects below the air temperature.

    Wind chill describes how skin feels: a pipe or a car doesn't get colder than the air.

  • Looking for frostbite risk above freezing.

    The air has to be below freezing for frostbite to develop on exposed skin.

  • Using the wind felt at ground level.

    The formula uses the wind measured at 10 m (33 ft), as in weather reports.

What the calculation leaves out

  • Sunshine isn't included: bright sunshine may raise the wind chill by 10 to 18 °F, according to the National Weather Service.
  • The risk levels are Environment Canada's. In sustained winds over 50 km/h (31 mph), frostbite can occur faster than indicated.
  • People react differently to cold: this is a general guide, not medical advice.

Wind chill by temperature and wind speed

Wind chill by temperature and wind speed
Temperature5 mph10 mph15 mph20 mph30 mph40 mph
40 °F363432302827
30 °F252119171513
20 °F139641-1
10 °F1-4-7-9-12-15
0 °F-11-16-19-22-26-29
-10 °F-22-28-32-35-40-43
-20 °F-34-41-45-48-53-57
-30 °F-46-53-58-61-67-71

Frequently asked questions

How is wind chill calculated?

With the NWS formula: 35.74 + 0.6215T − 35.75V^0.16 + 0.4275TV^0.16, T in °F and V in mph.

When is wind chill defined?

At or below 50 °F with winds above 3 mph, according to the National Weather Service.

When can exposed skin freeze?

From a wind chill of −28 °C (about −18 °F), exposed skin can freeze in 10 to 30 minutes, according to Environment Canada.

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