Wind chill, heat index and dew point in one weather calculator
How cold or hot it feels depends on more than the thermometer: wind strips heat from your skin, and humidity stops sweat from cooling you. This weather calculator takes the air temperature, relative humidity and wind speed and works out every common “feels like” measure at once — the wind chill used in the US and Canada, the US National Weather Service heat index, the dew point, Canada’s humidex and the Australian Bureau of Meteorology’s apparent temperature — with the official risk categories in colour.
Use it in °C or °F with wind in km/h, mph, m/s or knots. A second panel turns a dew point back into relative humidity. It is handy for planning a run in Chennai’s humid heat, a winter walk in Toronto, or checking whether a weather report’s numbers add up.
The calculations run in your browser and use only the numbers you type. They are informational and do not replace warnings from your weather service.
How to use the Weather Calculator
- Enter the Air temperature and choose °C or °F.
- Enter the Relative humidity in percent and the Wind speed with its unit (use the sustained wind, not gusts).
- Read the headline “feels like” value: wind chill when it is cold and windy, heat index when it is hot, apparent temperature in between.
- Look at each card for the value and its risk level; the marker on the coloured bar shows where you are.
- To get relative humidity from a dew point, fill in the second panel. Open Formulas used to see every equation.
Weather Calculator features
Five indices at once
Wind chill, heat index, dew point, humidex and apparent temperature, each with its own validity rules — the calculator says when an index is not defined.
Official risk bands
Environment Canada frostbite times for wind chill, NWS caution-to-extreme-danger levels for the heat index, Canadian humidex comfort levels and a common dew-point comfort guide.
Any units
°C or °F, and wind in km/h, mph, m/s or knots; switching temperature units converts the numbers you typed.
Dew point ↔ humidity
Magnus formula in both directions with the Alduchov–Eskridge constants, accurate to about 0.1 °C in normal weather.
Animated risk bars
Markers glide to the new level as you type; motion is removed if you prefer reduced motion.
Which “feels like” number should I use?
- Wind chill — for temperatures of 10 °C (50 °F) or below with wind of at least 4.8 km/h (3 mph). It estimates how cold exposed skin feels and how fast frostbite can develop.
- Heat index — from about 27 °C (80 °F) upward. It is calculated for shade and light wind; full sunshine can add up to 8 °C (15 °F).
- Humidex — Canada’s alternative to the heat index, computed from temperature and dew point. It is a number without units, but reads like degrees Celsius.
- Apparent temperature — the Australian measure that combines heat, humidity and wind across the whole range, without the effect of sunshine.
- Dew point — the best single measure of how muggy the air feels. Above about 21 °C (70 °F) most people find it oppressive.
Worked examples
| Conditions | Result |
|---|---|
| −10 °C, wind 30 km/h | Wind chill −19.5 °C — moderate risk |
| 0 °F, wind 15 mph | Wind chill −19 °F |
| 90 °F, 70% humidity | Heat index 106 °F (41 °C) — danger |
| 25 °C, 60% humidity | Dew point 16.7 °C — becoming sticky |
| 30 °C with dew point 15 °C | Humidex 34 — some discomfort |
| 30 °C, 50%, wind 2 m/s | Apparent temperature 31.6 °C |
Weather Calculator FAQ
How is wind chill calculated?
With the 2001 index adopted by the US National Weather Service and Environment Canada: WC = 13.12 + 0.6215T − 11.37V0.16 + 0.3965TV0.16, with T in °C and V in km/h. This weather calculator converts other units first.
Why is the heat index blank on a mild day?
The NWS heat index is only meaningful from about 80 °F (27 °C). Below that, the apparent temperature is used as the headline instead.
What is a comfortable dew point?
Below about 15 °C (60 °F) feels comfortable, 16–18 °C (60–65 °F) sticky, and above 21 °C (70 °F) oppressive.
Is humidex the same as heat index?
They aim at the same thing but use different formulas: humidex comes from the dew point and is usually a few degrees higher than the heat index for the same conditions.
How do I find the humidity ratio, wet bulb or enthalpy of air?
This weather calculator covers comfort indices. For the engineering properties of moist air — humidity ratio, wet-bulb temperature, enthalpy and specific volume at any altitude — use the psychrometric calculator, which follows the ASHRAE equations.
Does the calculator include sunshine?
No. All five indices assume shade. Direct sun makes it feel considerably hotter.
Can I convert the temperatures or wind speeds on their own?
Yes — use the temperature converter and the speed converter. Planning outdoor time? The sunrise and sunset calculator helps.