Humidex facts for kids
The humidex is a special number used by weather experts in Canada. It helps us understand how hot the weather *really* feels, especially when there's a lot of humidity in the air. Humidity is the amount of water vapor in the air. When it's hot and humid, it can feel much hotter than the actual temperature. For example, if the air temperature is 30 °C (86 °F), but the calculated humidex is 40, it means your body feels like it's 40 °C (104 °F). This number is often shared in Canadian weather reports during summer to show how uncomfortable the heat might be.
The humidex is different from the heat index used in the United States. The humidex uses the dew point (the temperature at which air becomes saturated with water vapor), while the heat index uses relative humidity.
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How Humidex Shows Discomfort
The Meteorological Service of Canada has rules for what different humidex numbers mean.
- A humidex of 30 or more means "some discomfort."
- If it reaches 40 or more, it causes "great discomfort."
- Above 45 is considered "dangerous."
- When the humidex hits 54, there's a very high risk of heat stroke.
Who Created the Humidex?
The way we calculate the humidex today was created in 1979. It was developed by J.M. Masterton and F.A. Richardson. They worked for Canada's Atmospheric Environment Service.
Canada's Highest Humidex Records
The highest humidex ever recorded in Canada happened on July 25, 2007. The town of Carman, Manitoba reached a humidex of 53.0. This broke the old record of 52.1. That record was set in 1953 in Windsor, Ontario. People in Windsor at that time wouldn't have known about the humidex, though, because it hadn't been invented yet!
Understanding the Humidex Formula
The humidex is a number that helps us understand how hot it feels. It combines the air temperature with the effect of humidity. For example, if the air temperature is 30 °C and the dew point is 15 °C, the humidex is 34. This means it feels like 34 °C.
If the air temperature stays at 30 °C but the dew point rises to 25 °C, the humidex goes up to 42. This shows that more humidity makes it feel much hotter. The humidex often gives a higher "feels like" temperature than the U.S. heat index for the same temperature and humidity.
The basic idea behind the humidex formula is:
- humidex = (air temperature in Celsius) + h
The h part of the formula accounts for the humidity. It uses the dew point temperature in kelvins to figure out how much the humidity adds to the "feels like" temperature.
Related pages
See also
In Spanish: Humidex para niños
