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WEATHER UNIVERSITY: When is a warm spell a heat wave?

Beach time at Marble Mountain, Cape Breton, N.S! Five-year-old Liam MacKinnon has the right idea: the best way to beat the heat is to get in the water and play.
Beach time at Marble Mountain, Cape Breton, N.S! Five-year-old Liam MacKinnon has the right idea: the best way to beat the heat is to get in the water and play. - Contributed

The “three Hs” are hanging around!

We enjoyed an interruption in the muggy weather July 30 with a brief, and very welcome, wind direction change.  Last week’s persistent south-westerlies came around to the west on Monday, but have settled back to where they’ve been pretty much all month.

We’ve been juggling with heat warnings for more than two weeks now.  Last week, I defined heat warnings and described how they vary from one province to another, but what about the term “heat wave?” Is this in fact a heat wave?

Well, that’s open to interpretation now.  There is no longer an official definition of a heat wave. Environment Canada removed the definition and never reinstated one, so it’s your call, I guess. A heat wave used to be defined as three or more consecutive days with temperatures of 32 degrees C or more and it didn’t take into account humidity. By that definition, St. John’s, N.L., and Vancouver, B.C., have never had a heat wave!

I think it’s safe to say we are experiencing a heat wave from Edmundston, N.B., to St. John’s, N.L. this month.

Cindy Day is the chief meteorologist for SaltWire Network.

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