Calculate feels-like temperature with the Bureau of Meteorology apparent-temperature model and published NWS heat-index and wind-chill methods.

Apparent Temperature Formula

The BoM mode uses the shade model below. Vapour pressure is e = (RH/100) × 6.105 × exp[17.27Ta/(237.7 + Ta)], with RH in percent. See the Bureau of Meteorology method.

AT = Ta + 0.33 × e - 0.70 × ws - 4
  • Where AT is the apparent temperature (°C)
  • Ta is the dry-bulb temperature (°C)
  • e is the water vapour pressure (hPa)
  • ws is the wind speed (m/s) measured at 10 m
  • The radiation term per unit body surface area belongs to a separate extended model and is not used by this shade calculator.

Apparent Temperature Definition

An apparent temperature is a temperature that it “feels” like in an environment due to the true temperature, humidity, and wind chill.

How is apparent temperature calculated?

An apparent temperature is calculated using the formula AT = Ta + 0.33*e – 0.70*ws – 4. This BoM version uses air temperature, vapour pressure and wind; it does not include direct solar radiation. NWS heat-index and wind-chill modes use separate published formulas. Automatic mode chooses qualifying heat index, then wind chill, otherwise BoM; this selection rule is a calculator heuristic.

What is reflected apparent temperature?

In infrared thermography, reflected apparent temperature represents radiation from the surroundings reflected by the target into a camera. It is separate from human feels-like temperature; this calculator does not measure it. See FLIR measurement parameters.

Apparent Temperature Example

How to calculate an apparent temperature?

  1. First, determine the dry-bulb temperature.

    Measure the dry-bulb temperature.

  2. Next, determine the humidity.

    Measure relative humidity as a percentage from 0 to 100.

  3. Next, determine the wind speed.

    Measure the wind speed.

  4. Next, calculate vapour pressure.

    Use e = (RH/100) × 6.105 × exp[17.27Ta/(237.7 + Ta)].

  5. Finally, calculate the apparent temperature.

    Select BoM mode and calculate with the measured temperature, relative humidity and wind. The shade estimate excludes solar radiation.

FAQ

Why does it feel hotter than it says on the thermometer?

The reason it feels hotter than the temperature in some situations is because of the effect wind and humidity have on the human body’s ability to cool down.

Apparent Temperature Calculator screenshot