Feels-like temperature calculator

In cold and windy conditions it calculates wind chill; in hot conditions with humidity it calculates the heat index. When neither formula is valid for the supplied conditions, it returns the measured temperature instead of extending an equation beyond its intended range. Results use the same Celsius or Fahrenheit unit as your temperature input.

One result from the weather data you have

A feels-like reading is not produced by one universal equation. Cold moving air increases heat loss from exposed skin, while hot humid air makes perspiration less effective at cooling the body. This calculator accepts an air temperature and whichever supporting observation is available: wind speed, relative humidity, or both. It first normalizes the values internally, then selects the formula whose published applicability conditions match them. The returned feels-like temperature stays in the temperature unit you selected, so a Celsius input produces Celsius output and a Fahrenheit input produces Fahrenheit output. The response also names the formula used. That explicit label matters in automated workflows because a downstream system can distinguish a calculated wind chill or heat index from a case where the measured air temperature was retained. At least one of wind speed and humidity must be present. Supplying both is encouraged when a weather station records both, because it lets the selector make the decision from a complete observation without requiring the caller to pre-classify the weather.

How automatic formula selection works

Wind chill is considered only when wind speed is above 3 miles per hour and the air temperature is 50 degrees Fahrenheit or lower, equivalent to about 4.8 kilometres per hour and 10 degrees Celsius. Within that range, the calculator uses the North American wind chill equation based on temperature and wind speed. If the cold-weather test does not apply, heat index is considered when relative humidity is supplied and the air temperature is at least 80 degrees Fahrenheit, about 26.7 degrees Celsius. The heat calculation uses the Rothfusz regression and its standard low-humidity and high-humidity adjustments. Near the lower boundary, the simpler preliminary heat-index estimate determines whether the full regression is appropriate. Wind chill receives priority only when its cold and windy conditions are actually met; therefore providing both observations does not create an arbitrary average of unrelated formulas. Outside both accepted ranges, the formula field is air_temperature and the feels-like value equals the measured temperature. This conservative fallback avoids presenting an unsupported extrapolation as meteorological precision.

Reading and using the result responsibly

The output contains the rounded feels-like temperature, the original air temperature, the temperature unit, and the formula selected. Use the formula field when displaying a label such as wind chill or heat index, and retain the measured value when you need an audit trail. The result describes standardized outdoor exposure conditions; it is not a personalized medical forecast. Sunlight, shade, clothing, activity, age, health, wind shelter, and local microclimates can all change how a person experiences the same observation. Weather agencies may also publish values based on station sampling rules or rounding that differ slightly from a calculation using raw inputs. For operational alerts, compare the result with the thresholds and official guidance appropriate to the location rather than treating the number alone as a safety decision. The calculator is deterministic and performs no network lookup, so it will not fetch current weather or infer missing observations. That makes it suitable for processing sensor readings, archived datasets, and forecast values where you already control the source and timestamp of each input.