Feels Like Temperature Calculator
Calculators · Added
A thermometer reports the air and nothing else. What a body registers depends on how fast moisture can evaporate from skin and how quickly moving air carries heat away — which is why 32 °C at 80% humidity is punishing and 32 °C in dry desert air is merely hot. This calculator applies the two published models meteorologists actually use, states which one it ran, and says so plainly when neither of them applies.
How to use the feels like temperature calculator
- 1Enter the air temperature and pick °C or °F.
- 2Enter the relative humidity as a percentage — every forecast page lists it.
- 3Enter the wind speed, in whichever unit you have it. Use 0 for still air.
- 4Press Calculate.
- 5Read which model ran. Above about 27 °C it is the heat index, at or below 10 °C with wind it is wind chill, and in between neither applies — the tool says so rather than inventing a figure.
Examples
Humidity doing the damage
- Input
- 35 °C, 70% humidity, light wind
- Result
- Feels like about 50 °C — the Danger band, where heat exhaustion is likely
Fifteen degrees above the air temperature. Sweat cannot evaporate into air that is already most of the way to saturated, and evaporation is how a body sheds heat.
The same heat, dry
- Input
- 40 °C, 10% humidity, any wind
- Result
- Feels like about 37 °C — below the air temperature
Dry air lets sweat evaporate freely, so it feels cooler than the thermometer reads. This is the dry-heat correction the NWS formula applies below 13% humidity.
Wind stripping heat away
- Input
- -5 °C, 60% humidity, 30 km/h wind
- Result
- Feels like about -13 °C, with frostbite guidance attached
Humidity is not in the wind chill formula at all — at these temperatures the air holds very little moisture either way, and the model that governs is heat loss to moving air.
About the feels like temperature calculator
Two formulas, two different physics
Heat index and wind chill are not two settings of one idea. They describe opposite problems, and they are built from different measurements.
In heat, the body's cooling mechanism is evaporation: sweat takes energy with it as it turns to vapour. How readily that happens depends on how much water the surrounding air can still absorb, which is what relative humidity measures. As humidity climbs the mechanism stalls, core temperature rises and the same air temperature becomes progressively more dangerous. The heat index is a regression fitted to Steadman's tables of apparent temperature, and it carries two corrections at the corners where the plain fit drifts — one that makes very dry heat read cooler, one that makes very humid heat at moderate temperatures read hotter.
In cold, the mechanism is convection: still air trapped against the skin forms an insulating layer, and moving air strips it away, so heat leaves faster even though the air's temperature has not changed. Wind chill quantifies that as the still-air temperature which would cool exposed skin at the same rate. It is why the figure is described as what the air feels like on bare skin rather than as a temperature anything actually reaches — a thermometer in the wind still reads the air temperature, and a bottle of water outside will not freeze any faster because of it.
What the models leave out
Both are models of an average person in specific conditions, and the conditions are worth knowing. The heat index assumes shade. Standing in full sun can add roughly 8 °C to the effective figure, which is enough to move a reading from Extreme Caution into Danger without the weather changing at all.
Wind chill assumes the wind speed used in forecasts, measured at the standard 10 m height, and it applies to exposed skin. Wind at head height is slower, so a hand-held reading makes the calculated chill slightly conservative — and clothing changes the answer entirely, which is the point of it. The frostbite times attached to the colder bands are the published guidance for bare skin, not a general safety threshold for a dressed person.
Neither model knows anything about you. Age, body composition, medication, hydration, acclimatisation and exertion all move the real answer, sometimes by a lot: someone who has spent a fortnight in the heat tolerates it measurably better than someone who arrived yesterday. That is why the bands on this page are worded as guidance rather than as a verdict, and why nothing here is a substitute for a local heat or cold advisory.