Wind Chill & Heat Index Calculator
What the weather really feels like: wind chill in the cold, with how fast exposed skin can freeze, and the heat index in hot, humid weather, with the risk of heat illness.
Last updated
Feels like
—
Wind chill and frostbite
| Wind chill | Risk | What it means |
|---|
How to work out the feels-like temperature
- Enter the air temperature, the wind speed and the humidity from your weather forecast.
- In the cold (10 °C / 50 °F or below, with some wind) you get the wind chill and how quickly exposed skin can freeze.
- In the heat (27 °C / 80 °F or above) you get the heat index and the risk of heat illness.
The formulas
Wind chill uses the formula shared by the US National Weather Service and Environment Canada since 2001: in °C and km/h, 13.12 + 0.6215T − 11.37V0.16 + 0.3965TV0.16. It applies at 10 °C (50 °F) or colder with wind over 4.8 km/h (3 mph), and estimates how cold it feels on exposed skin. The frostbite times are Environment Canada’s: from −28 wind chill, exposed skin can freeze within 10 to 30 minutes, and faster in stronger wind.
Heat index uses the National Weather Service’s method: Rothfusz’s regression in °F, with its adjustments for very dry and very humid air, and a simpler formula below about 80 °F. It describes how hot it feels in the shade with a light wind; full sun can make it feel up to 8 °C (15 °F) hotter. The risk levels are the National Weather Service’s.
These are guides, not limits: children, older people, people with health conditions and anyone working hard outdoors are at risk sooner.
Sources
Checked on 18 October 2026.
- National Weather Service: Wind chill chart the wind chill formula and where it applies.
- Environment Canada: Wind chill index risk levels and how fast exposed skin can freeze.
- NOAA Weather Prediction Center: The heat index equation the Rothfusz regression and its adjustments.
- National Weather Service: Heat index risk levels, and full sun adding up to 15 °F.
Questions about feels-like temperature
What is wind chill?
How cold it feels on exposed skin when the wind carries heat away. At −10 °C with a 30 km/h wind, it feels like about −20 °C.
When can frostbite happen?
At a wind chill of −28 or colder, exposed skin can freeze within 10 to 30 minutes, and within 2 to 5 minutes at −48 or below. Cover your face, ears and hands.
What is the heat index?
How hot it feels when humidity stops sweat from cooling you. At 32 °C and 60% humidity it feels like about 37 °C, where heat cramps and heat exhaustion are possible.
Why does the feels-like temperature only show wind chill or heat index?
Wind chill is only defined at 10 °C (50 °F) or below, and the heat index from about 27 °C (80 °F). In between, the feels-like temperature is close to the air temperature.