It’s been quite a summer. Many are wishing it gone, while others are basking in the heat. Last weekend a neighbour asked me if we were in a heatwave right now. Well, that’s open to interpretation; there is no longer an "official" definition for the term “heatwave." Environment Canada removed the definition and never reinstated one, so it’s your call I guess.
A heatwave used to be defined as three or more consecutive days with temperatures of 32 degrees Celsius or more. The warnings did not take humidity into account. Based on that definition, St. John’s, N.L. and Vancouver, B.C. have never had a heatwave! Now you can probably see why that was flawed.
Heat warnings, however, are clearly defined. There are two categories: those triggered by very warm air temperatures and those brought on by very high humidity levels. In the case of heat warnings, you’ll find regional variation; the temperature threshold would not be the same in central Alberta, as it would be in central Labrador.
Heat warnings are issued when the following conditions are forecast:
NEW BRUNSWICK:
- Two consecutive days with daytime highs at or above 30 degrees C and overnight lows of 18 degrees or warmer
OR
- Two or more consecutive days with a humidex reading of 36 or more.
NOVA SCOTIA:
- Two consecutive days with daytime highs at or above 29 degrees C and overnight lows of 16 degrees or warmer
OR
- Two or more consecutive days with a humidex reading of 36 or more.
PRINCE EDWARD ISLAND:
- Two consecutive days with daytime highs at or above 27 degrees C and overnight lows of 18 degrees or warmer
OR
- Two or more consecutive days with a humidex reading of 35 or more.
NEWFOUNDLAND AND LABRADOR
- Two consecutive days with daytime highs at or above 26 degrees C and overnight lows of 15 degrees or warmer
OR
- Two or more consecutive days with a humidex reading of 34 or more
Stay cool and hydrated, and be especially vigilant around the very young and the elderly; keep an eye on your pets too! Do your best to enjoy the summer; in less than 5 months, we’ll be sharpening our skates for a twirl on a frozen pond.
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- Have a weather question, photo or drawing to share with Cindy Day? Email weathermail@weatherbyday.ca
Cindy Day is the chief meteorologist for SaltWire Network
