Editorially reviewedReviewed by Agarapu Ramesh, science educator (chemistry). LinkedIn
Last reviewed: May 2026|Standard temperature conversion formulas
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
e = (RH / 100) x 6.105 x exp(17.27T / (237.7 + T)); AT = T + 0.33e - 0.70ws - 4.00
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.
Practical note: Apparent temperature is a comfort indicator, not a replacement for air temperature or a universal heat-safety rule. Real exposure depends on shade, sun, clothing, and workload as well as the modeled variables.
"Feels Like" index used in Australia (BOM).
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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.
Enter 33 for air temperature.
Enter 55 for relative humidity.
Enter 3 for wind speed.
The humidity raises the feels-like value, while wind offsets part of that increase.
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.
Station Apparent Temperature
Station apparent temperature combines weather station readings such as air temperature, humidity, and wind into a feels-like estimate. Use it for comfort screening, then check the specific heat index, wind chill, or WBGT page when the situation needs a standard method.
Frequently Asked Questions
The Steadman/BOM formula is the one I keep coming back to: AT = T + 0.33e − 0.70ws − 4.00, where T is air temperature in °C, e is water vapour pressure in hPa, and ws is wind speed at 10 m in m/s. Vapour pressure comes from RH and temperature. For example, at 32°C, 60% RH, and 2 m/s wind, AT lands near 35°C — that extra "feel" is mostly the humidity dragging your evaporative cooling down.
The Australian Bureau of Meteorology version is AT = Ta + 0.33e − 0.70ws − 4.00, where Ta is the dry-bulb air temperature in °C, e is vapour pressure in hPa, and ws is the 10-metre wind speed in m/s. It is valid in shade — radiation from direct sun is not in this equation. For a sunlit version, BOM has an extended form that adds a net radiation term Q in W/m2. Always check which one your data source is using.
"Feels like" is what your body reports, not what the thermometer reports. The mercury reads air temperature alone, but your skin is reacting to humidity, wind, and radiation as well. On a humid 30°C afternoon, sweat does not evaporate well, so heat builds and you feel closer to 36°C. On a windy 5°C morning, fast convection strips warmth from your skin, so it feels nearer to −2°C. The number is an estimate of physiological perception, not a physical measurement.
Practically yes, but the wording is loose. "Apparent temperature" is the formal scientific term — the Steadman index used by BOM and many national services. "Feels-like temperature" is the consumer-friendly label your weather app puts on it. In some countries the app actually shows heat index or humidex or wind chill depending on conditions, and just labels it "feels like." So always check the source: same idea, but the underlying formula can change with the season and the agency.
Humidity slows the evaporation of sweat, which is your main cooling channel — so on a muggy day your body cannot shed heat efficiently and the apparent temperature rises. Wind has two faces. When it is colder than your skin, it pulls heat away by forced convection and lowers what you feel — that is the wind chill effect. But on a very hot, dry day, wind from a hotter source can actually push the apparent temperature up. Direction and conditions matter.
The BOM formula in shade is AT = Ta + 0.33e − 0.70ws − 4.00, with Ta in °C, vapour pressure e in hPa and wind ws in m/s. Unlike the US heat index, it works across the whole temperature range, not just hot conditions, and unlike wind chill it includes humidity. So a single equation handles a humid 35°C summer day and a breezy 8°C winter morning. This year-round flexibility is why Australia and several other countries adopted it.
Three inputs go in: dry-bulb air temperature, relative humidity, and wind speed. The calculator first turns RH into vapour pressure using a Magnus or Tetens approximation, then plugs everything into the Steadman equation. So if you have 33°C, 65% RH, and 3 m/s wind, the tool computes e ≈ 21 hPa, then AT ≈ 33 + 6.9 − 2.1 − 4.0 ≈ 33.8°C. Make sure wind is measured at 10 m height — surface readings will skew the result.
The thermometer only sees one variable — air temperature. Your body sees four: temperature, humidity, wind, and radiation. The app's "feels-like" number runs all of them through a perception model and reports what an average person in shade would experience. So on a 28°C afternoon with 80% humidity, the app might say 33°C, while in dry, breezy 28°C it might say 26°C. The air temperature has not changed; the heat budget on your skin has.
