Weather calculators
Five calculators built on published formulas — the National Weather Service heat index and wind chill equations, the Fitzpatrick UV scale and the Saffir-Simpson hurricane scale. Each one runs on the server and explains what the result means for you, in Fahrenheit, miles per hour and inches.
Heat index calculator
Combine temperature and humidity to find out what the air actually feels like, and how close that is to dangerous.
Wind chill calculator
Find out how much colder the wind makes it feel, and how many minutes exposed skin has before frostbite sets in.
UV index and sunburn time calculator
Estimate how many minutes of sun your skin can take before it burns, by UV index, skin type and sunscreen.
Hurricane category calculator
Turn a sustained wind speed into a Saffir-Simpson category, with the damage description and the real wind force behind it.
Weather unit converter
Convert between Fahrenheit and Celsius, mph and km/h, inches of mercury and millibars, and more.