Enter the air temperature and the wind speed to get the wind chill (how cold it actually feels) and an estimate of how quickly exposed skin could suffer frostbite.
Wind chill is not meaningful in these conditions: the formula only applies to air temperatures at or below 10°C (50°F) with a wind speed of at least 4.8 km/h (3 mph). At this temperature and wind speed, the air temperature itself is the best estimate of how it feels.
| Wind chill range | Frostbite risk on exposed skin |
|---|---|
| Above -15°C (5°F) | No significant risk in the short term |
| -15°C to -28°C (5°F to -19°F) | Frostbite possible in around 30 minutes |
| -28°C to -51°C (-19°F to -60°F) | Frostbite possible in around 10 minutes |
| Below -51°C (-60°F) | Frostbite possible in under 5 minutes |
Wind chill is a comfort and risk index, not a direct physical measurement of temperature. It does not replace official weather warnings. In severe cold, follow the advice and alerts issued by your local weather authority.
Why the wind makes cold air feel colder
Air temperature only tells part of the story on a cold day. Skin is always losing a thin layer of warmed air right against its surface, and still air lets that layer build up as a kind of insulating buffer. Wind strips that buffer away as fast as it forms, forcing the skin to keep giving up heat to warm a fresh layer of cold air, which is why a 0°C day with a stiff breeze can feel far harsher than the thermometer suggests. Wind chill converts air temperature and wind speed into a single "feels like" figure using the formula adopted by the US National Weather Service and Environment Canada in 2001, the same standard used by the UK Met Office and most national weather services.
Frostbite risk by wind chill
| Wind chill range | Frostbite risk on exposed skin |
|---|---|
| Above -15°C (5°F) | No significant risk in the short term |
| -15°C to -28°C (5°F to -19°F) | Frostbite possible in around 30 minutes |
| -28°C to -51°C (-19°F to -60°F) | Frostbite possible in around 10 minutes |
| Below -51°C (-60°F) | Frostbite possible in under 5 minutes |
What this calculator cannot do
The formula is only defined for air temperatures at or below 10°C (50°F) and wind speeds of at least 4.8 km/h (3 mph); outside that range the wind has little measurable cooling effect and the tool reports the air temperature itself as the best estimate. It also leaves out humidity, direct sunshine, and clothing: a sunny, sheltered spot can feel noticeably warmer than the wind chill figure, while wet clothing or skin makes the cold feel worse than it predicts. Treat the result as a general guide to cold exposure risk, not a precise medical or physical measurement.
Met Office cold weather alerts
The Met Office issues Cold Weather Alerts and amber or red weather warnings when a spell of low temperatures and strong wind is expected to put vulnerable people at risk, often during a winter storm such as the "Beast from the East" cold snaps that have hit the UK in recent years. If a cold weather alert is in force, check on elderly neighbours and relatives, keep an eye on pets left outdoors, and limit the time spent outside with skin exposed rather than relying on this calculator alone as a safety guide.