Why does −10 °C feel like −20 on a windy day, or 30 °C feel like 38 when it's muggy? Move the sliders and see the wind chill and humidex that Environment Canada uses.
Wind carries body heat away faster, so bare skin cools as if it were colder. Environment Canada reports wind chill when the temperature is 0 °C or lower and the wind is above about 5 km/h. This page shows it up to 10 °C.
T in °C, V in km/h at 10 m height.
Risk: −10 to −27 is cold and uncomfortable. −28 to −39 means exposed skin can freeze in 10 to 30 minutes. −40 to −47 means in 5 to 10 minutes. −48 and colder means in under 5 minutes.
Humid air makes it harder for sweat to cool you, so muggy days feel hotter. Humidex combines temperature and dew point and is used from about 25 °C up.
Td is the dew point in kelvins.
Comfort: under 30, little discomfort. 30 to 39, some discomfort. 40 to 45, great discomfort, so avoid exertion. Over 45, dangerous, and heat stroke is possible.
Formulas and risk levels follow Environment and Climate Change Canada's wind chill and humidex guidance. This page is for learning; follow official weather warnings.