Wave goodbye to those heatwaves

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

Recently, a co-worker asked me if we are in the start of the first heatwave of the season. The thing is heatwaves have changed in Canada. Let me explain.

Heatwaves 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, that means there has never been a heatwave in St John's or Vancouver. Really?

That definition of a heatwave isn't necessarily accurate for the effects it has. It can be misleading because it only considers the high temperature for the day, and not the overnight low or the humidity. It misses the point, that is, the effect it has on humans.

Prompted by health officials studying the impact of deadly heat, the system used by Environment Canada to alert the public of dangerous heat changed a couple of years ago. Heat warnings replace humidex advisories, include consecutive warm days and nights, and factor in the humidity.

Heat warnings are issued when the following conditions are forecast:

NEW BRUNSWICK:

Two consecutive days with daytime highs at or above 30° C, and overnight lows of 18° C or warmer. Or two or more consecutive days with a humidex reading of 36° C or more.

NOVA SCOTIA:

Two consecutive days with daytime highs at or above 29° C, and overnight lows of 16° C or warmer. Or two or more consecutive days with a humidex reading of 36° C or more.

PRINCE EDWARD ISLAND:

Two consecutive days with daytime highs at or above 28° C, and overnight lows of 18° C or warmer. Or two or more consecutive days with a humidex reading of 35° C or more.

NEWFOUNDLAND AND LABRADOR

Two consecutive days with daytime highs at or above 28° C, and overnight lows of 16° C or warmer. Or two or more consecutive days with a humidex reading of 34° C or more.

The revamped heat warnings should 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.

Globally, heatwaves kill more people than tornadoes do.

CONTRIBUTED You can always find relief from the heat on the water. The warm tones in this stunning photo taken near Bateston, in Cape Breton Regional Municipality, belie the cool air rising off the water. Josephine Kennedy says if you look closely, you can see lobster boats hauling their traps across Mira Bay.