Dew point, wet bulb, heat index and wind chill

Dew point inverts the Bolton liquid-water vapour-pressure equation using temperature and relative humidity. Wet bulb uses Stull’s sea-level approximation. Heat index uses the NWS simple formula or Rothfusz regression with low/high-humidity adjustments. Wind chill uses the NWS temperature and wind-speed relationship.

Reference: UCAR vapour pressure · Reference: Stull wet bulb · Reference: NWS heat index · Reference: NWS wind chill

The result above uses these exact values. This snapshot is included when the page is printed so the output can be checked against the original measurements.

Weather temperature model

Dew point

Air temperature

20 °C

Relative humidity

50 %

Primary result: Dew point: 9.27008599 °C.

• Check the selected mode, units and input values before using the result.
• Read the assumptions and rounding rules; compare the worked example with your intended calculation.
• A numerical result does not supply missing context or change the stated limitations.

Dew point: −30–50°C and humidity above 0% through 100%. Wet bulb: 0–50°C, 5–99% humidity, sea-level pressure. Heat index: 80–110°F air temperature, with calculated index no higher than 137°F; it assumes shade and light wind. Wind chill: −50–10°C and wind above 3 through 60 mph. Out-of-range combinations are rejected. These indices do not replace measured conditions, official warnings or individual health assessment.