Weather Calculations

Weather Calculations is the only weather calculator you will need.  It contains 6 calculators in one: Heat Index, Wind Chill, Dew Point, Apparent Temperature, Humidex, and Wet Bulb Globe Temperature.

This calculator handles both imperial and metric units (with built-in unit converter).  Enter the air temperature in Fahrenheit or Celsius.  Enter the wind speed in miles per hour, meters per second, kilometers per hour, or knots.  Many more units included!

Compare various models to see which matches how you perceive the weather.  Explore what-if scenarios to better understand weather modeling.


**Heat Index Calculator**
Heat Index calculates the Heat Index from models by the US National Weather Service.

Notes: Heat Index is defined for temperatures above 80 degrees F (27 degrees C) and relative humidity above 40%.  Calculator may not be accurate outside those ranges.


**Wind Chill Calculator**
Wind Chill calculate the wind chill using both the new (post-2001) and old (pre-2001) Windchill Temperature (WCT) index from models by the US National Weather Service.  It also provides the old Windchill Index in kcal/m^2/h.

Notes: Windchill Temperature is defined for temperatures below 50 degrees F (10 degrees C) and wind speeds above 3 mph (4.8 kph or 1.34 m/s).  Calculator may not be accurate outside those ranges.


**Dew Point Calculator**
Unlike some calculators which only calculate the dew point temperature, the Dew Point Calculator will also calculate the air temperature given the dew point temperature and relative humidity as well as calculate the relative humidity given the air temperature and the dew point temperature.

This calculator uses the more accurate August-Roche-Magnus model and is accurate for temperatures between 32°F (0°C) and 140°F (60°C).


**Humidex Calculator**
Humidex is a quick heat index calculator.  Want to know the effect of humidity on how hot it feels?

Humidex calculates the humidex from models by the Meteorological Service of Canada.

**Apparent Temperature Calculator**
Apparent Temperature uses the three factor model developed by the Australian Bureau of Meteorology, which assumes a sunny day.

This advanced model works for high and low temperatures, combining the effects of humidity and wind chill into a single 'feels like' apparent temperature.


**Wet Bulb Globe Temperature Calculator**
Wet Bulb Globe Temperature is an estimate of how hot it feels with humidity?

Enter the temperature and relative humidity, and Wet Bulb Globe Temperature calculates the WBGTI describing how temperature and humidity feels.  Flag indicators help you to quickly identify the risks of outdoor activities.  These indicators are based on the system used by the USMC (see: http://www.mcrdpi.usmc.mil/weather.asp for more details).

This WBGT index calculator uses the same approximation as the Australian Bureau of Meteorology for estimating the Wet Bulb Globe Temperature from the air temperature and relative humidity, assuming sunny day and light wind.  On cloudy or windy days, this is an overestimation of how hot it feels.