What this calculator does

This apparent temperature calculator estimates how warm or cool outdoor air feels when temperature, humidity, and wind act together. It is useful when moisture matters but moving air also changes how the body exchanges heat with the environment.

In warm weather, humidity can make the body feel hotter by reducing evaporative cooling. At the same time, wind can improve cooling and lower the feels-like burden. Apparent temperature brings those effects together in one simple estimate, which makes it helpful for forecast interpretation and plain-language communication.

Inputs explained

• Air temperature: Enter the dry-bulb air temperature.
• Relative humidity: Enter the current moisture level as a percentage.
• Wind speed: Enter the wind speed in the units expected by the page so the calculator can apply the wind cooling term correctly.

How it works / method

The page uses a Bureau of Meteorology style apparent temperature estimate. It converts humidity to vapor pressure and then adjusts the dry-bulb temperature with a moisture-warming term and a wind-cooling term. The result is a concise feels-like number that is easier to compare across forecast periods than raw variables alone.

Formula used

T is air temperature in C, e is vapor pressure in hPa, and ws is wind speed in m/s. Because this is an index, the output should be interpreted as perceived thermal burden rather than a new measured air temperature.

Step-by-step example

Suppose the air temperature is 33 C, relative humidity is 55 percent, and wind speed is 3 m/s. The apparent temperature balances moisture-driven warming and wind-driven cooling.

1. Enter 33 for air temperature.
2. Enter 55 for relative humidity.
3. Enter 3 for wind speed.
4. The humidity raises the feels-like value, while wind offsets part of that increase.
5. If wind drops but humidity stays high, the apparent temperature climbs.

Use cases

• Comparing warm-weather forecasts when both humidity and breeze differ from one day to the next.
• Communicating why a windy humid day can feel different from a calm humid day even at the same dry-bulb temperature.
• Supporting public-facing weather summaries that need more nuance than air temperature alone.
• Screening general outdoor comfort before moving to more formal heat-stress tools.

Assumptions and limitations

• Apparent temperature is a modeled human comfort estimate and should not be read as a measured physical air temperature.
• The quality of the output depends on accurate humidity and wind inputs and on the chosen approximation.
• It does not replace direct WBGT-based safety management for intense sun or work-rest planning.
• Individuals can feel substantially different under the same environmental conditions.

Use apparent temperature for quick interpretation. Use heat index when you want a simpler shaded humidity index, or WBGT when you need a more explicit heat-stress signal.

Sources & references

• NOAA National Weather Service - Heat index guidance
• NOAA National Weather Service - Wind chill chart and formula
• NOAA National Weather Service - Wet Bulb Globe Temperature overview
• Bureau of Meteorology - Apparent temperature background
• Bureau of Meteorology - Apparent temperature glossary
• Environment and Climate Change Canada - Humidex guidance
• Schema.org - FAQPage and WebApplication vocabulary