What is apparent temperature?

Apparent temperature is the perceived or "feels-like" temperature experienced by the human body, factoring in air temperature, relative humidity, and wind speed. It was developed by R.G. Steadman and is used operationally by the Australian Bureau of Meteorology.

What formula does this calculator use?

It uses the Australian BOM formula: AT = Ta + 0.33 × e − 0.70 × ws − 4.00, where Ta is air temperature (°C), e is water vapour pressure (hPa) derived from humidity, and ws is wind speed (m/s). Water vapour pressure: e = (rh / 100) × 6.105 × exp(17.27 × Ta / (237.7 + Ta)).

How is apparent temperature different from heat index or wind chill?

Heat index only accounts for humidity, wind chill only accounts for wind, and both are region-specific. The BOM apparent temperature formula combines both factors across the full temperature range, making it more broadly applicable.

What humidity range is valid?

Relative humidity should be between 0% and 100%. Values outside this range are physically meaningless; the calculator clamps them to this range automatically.

Why does the apparent temperature sometimes exceed air temperature?

High humidity reduces the body's ability to cool itself through sweat evaporation, so the perceived temperature rises above the actual air temperature. At low humidity and high wind, the apparent temperature can fall below air temperature.

At what apparent temperature is heat stress a concern?

Generally, AT above 32 °C (90 °F) warrants caution; above 41 °C (106 °F) is dangerous; above 54 °C (130 °F) is extreme and potentially life-threatening. Cold stress begins below 10 °C (50 °F).

Apparent Temperature Calculator

Name: Apparent Temperature Calculator
Availability: InStock
Author: Nham Vu

Calculate the apparent (feels-like) temperature using the Australian BOM formula with air temperature, relative humidity, and wind speed inputs.

Inputs

Units:

Air Temperature (°C)

Relative Humidity (%)

Wind Speed (km/h)

Enter values and click Calculate

Comfort Level Reference

Apparent Temp (°C)	Apparent Temp (°F)	Comfort Level
Below −10	Below 14	Very Cold — Severe cold stress risk
−10 to 0	14 to 32	Cold — Cold stress likely
0 to 10	32 to 50	Cool — Light layers recommended
10 to 25	50 to 77	Comfortable
25 to 32	77 to 90	Warm — Caution advised
32 to 41	90 to 106	Hot — Heat stress possible
Above 41	Above 106	Dangerous — Heat stroke risk

Summary

Calculate the apparent (feels-like) temperature using the Australian BOM formula with air temperature, relative humidity, and wind speed inputs.

How it works

Enter the air temperature, relative humidity, and wind speed.
Water vapour pressure (e) is derived from humidity using the Magnus formula.
Wind speed is converted to m/s for the BOM equation.
The formula AT = Ta + 0.33 × e − 0.70 × ws − 4.00 is applied.
The result is displayed alongside a comfort-level label.

Use cases

Assess outdoor comfort before exercise or a sporting event.
Determine whether conditions feel dangerously hot or cold.
Verify weather app "feels like" readings against the BOM formula.
Teach students how humidity and wind combine to alter perceived temperature.
Plan outdoor work schedules around safe heat-stress thresholds.
Compare apparent temperatures across different climate conditions.

Frequently Asked Questions

Last updated: 2026-06-15 · Reviewed by Nham Vu