Example preset
Inputs
Open-Meteo is contacted only after you search or click Get current weather; place names and coordinates are sent for lookup. Pressure uses sea-level pressure (MSL).
Calculation result
| Heat index (HI) | — |
|---|---|
| Wind Chill | — |
| saturated water vapor pressure es | — |
| water vapor pressure e | — |
| Absolute humidity AH | — |
| Humidex (reference) | — |
| Mixing ratio w | — |
| specific humidity q | — |
RH sensitivity chart (temperature fixed)
—
Calculation assumptions/application conditions
- We calculate dew point with the Magnus approximation and switch coefficients by the sign of T.
- We calculate wet bulb temperature with the Stull (2011) approximation and show a warning outside its recommended range.
- The tool uses corrected sea-level pressure (MSL) at the selected point. If you need local pressure, enter it manually.
- Heat index and wind chill show N/A outside their valid conditions.
- These outputs are approximate reference values. Do not use them for safety-critical or medical decisions.
FAQ
What is dew point temperature?
This is the approximate temperature at which condensation begins when the air cools with a constant amount of water vapor.
Is wet bulb temperature an exact calculation?
No. The tool uses the fast Stull approximation. If your case is outside the recommended range, it still shows a reference value with a warning.
Why is the heat index and wind chill set to N/A?
Each metric has valid conditions. When your inputs fall outside those conditions, the tool shows N/A to avoid misleading output.
Can I leave the barometric pressure and wind speed blank?
Yes. Indicators that need missing inputs show N/A, while other indicators still calculate normally.
Why are the numbers a little different from other sites?
Differences occur due to differences in approximation formulas, preconditions, and rounding methods. Please use this as a reference value for learning and rough calculations.
Which weather-derived metric should you read?
Dew point
Dew point answers a humidity question: how much moisture is in the air, and at what temperature condensation would begin if the air cooled without changing water vapor content. Higher dew points usually feel more humid.
Wet bulb temperature
Wet bulb temperature combines temperature and humidity through an evaporation-based approximation. It is useful for learning and rough comparison, but it is not a substitute for official heat-stress guidance or workplace safety rules.
Heat index and wind chill
- Heat index applies to hot, humid conditions and is hidden as N/A outside its valid range.
- Wind chill applies to cold, windy conditions and is hidden as N/A outside its valid range.
- Apparent temperature is a broader reference metric; compare it with the inputs before treating it as a decision rule.
Input checks before comparing results
Keep the same temperature unit, humidity basis, pressure assumption, and wind-speed unit across runs. If you are comparing locations, note whether pressure is sea-level pressure or a manually entered local value.
Related tools
- Earth science/environment (atmosphere/weather (sun/humidity/air quality))
- Solar altitude, direction, sunrise/sunset, day length
- Atmospheric pressure ↔ Altitude (standard atmosphere/sea level correction)
- AQI: Measured value → index/class display (method selection)
- ppm/ppb ↔ mg/m³ conversion (gas: molecular weight, temperature, pressure)