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WEATHER U: Old-fashioned heat waves are history

When summer starts to sizzle, many Atlantic Canadians are fortunate to have some water around to play in.  Earlier this week, Warren Hoeg escaped the city heat by spending some time at one of our lovely beaches. On Tuesday, he and many others found some relief from the heat at Taylor Head Provincial. Park Beach, Eastern Shore, N.S. - Warren Hoeg
When summer starts to sizzle, many Atlantic Canadians are fortunate to have some water around to play in. Earlier this week, Warren Hoeg escaped the city heat by spending some time at one of our lovely beaches. On Tuesday, he and many others found some relief from the heat at Taylor Head Provincial. Park Beach, Eastern Shore, N.S. - Warren Hoeg - Contributed

OK, so that headline might be a little misleading, but it did get your attention, didn’t it?

The other day a construction worker asked me if this warm weather was considered a “heat wave.”

Heat waves are changing in Canada. Let me explain.

A heat wave has never really had a formal definition. In some documents, you’ll find it described as three or more consecutive days with a temperature of 32 C or more. By those standards, there’s never been a heat wave in St. John’s, N.L., or Vancouver, B.C. Really?

That definition of a heat wave isn’t necessarily accurate for the effects it has. It can be misleading because it only takes into account the high temperature for the day and not the overnight low or the humidity. It misses the point on the effect it has on humans.

So, prompted by health officials studying the impact of deadly heat, the system Environment Canada uses to alert the public to dangerous heat has been changing. Heat warnings replace humidex advisories and include consecutive warm days and nights and factor in the humidity. (Those numbers can be found in Wednesday’s Weather University column).

The revamped heat warnings are meant to encourage the public to take precautions at extreme temperatures. This will become even more important moving forward. Experts predict that over the next 30 years, the number of extremely hot days in a year is expected to more than double in some parts of Canada.

Already, heat waves kill more people globally than tornadoes do.

RELATED: Heat warnings - whether or not



Cindy Day is the chief meteorologist for SaltWire Network.


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