Canadians can count on a more ‘normal’ summer this year

Scott Sutherland

With Victoria Day being an unofficial start of summer in the minds of Canadians, thoughts are turning to what the weather is going to be like for us over the next few months, and so far it's looking like we'll have a return to a more normal summer than we've seen over the past few years.

The latest forecasts are still painting warmer-than-normal temperatures across the country for this summer, but they're not expected to be anywhere close to the punishing heat experienced in the summers of 2011 and 2012. It's looking like the southern parts of B.C., Alberta and Saskatchewan, as well as southern Ontario and nearly all of Quebec and the Maritimes will be seeing slightly warmer temperatures to start the season off, with the rest of the country following suit into July and August.

Rainfall amounts seem to be fairly normal as well, with some slightly drier conditions expected to start, and then gradually increasing throughout the season, with B.C. south coast possibly getting a bit of a wet end to the summer.

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These are, of course, averaged out. No doubt, we're still going to see temperatures above 30°C, we're still going to see a few heat waves and we're still going to have some record-breaking temperatures. However, overall, it likely won't compare to what we've seen over the past two years.

The reason for this? No, global warming hasn't stopped. Globally-averaged temperatures are still rising steadily, and the temperature trend for Canada's summers is also still on the rise (see the graph). The specific reason for us returning to a more 'typical' summer is a shift in the El Niño Southern Oscillation (ENSO). This pattern of winds and ocean currents normally pushes warmer waters west from South America towards Australia, causing cooler water to well up from deep in the ocean near Peru (its negative or 'La Niña' phase), but it periodically breaks down, causing those warmer waters to 'slosh' back towards the east (its positive or 'El Niño' phase).

Over the past two years, ENSO has been in a strong La Niña phase, with the one in 2010/2011 apparently being the strongest on record. With an exceptionally strong La Niña, it shifts weather patterns, bringing sweltering heat and drought conditions to North America. This year, ENSO is in a more 'neutral' phase (technically a very weak La Niña), so we'll be seeing a summer more like what we're used to.

For comparison, summer of 2012 ranked as the hottest summer since the national temperature record started back in 1948, according to Environment Canada, beating out the previous record summer from 1998.

It started off with a 'bang', just before the official start of the season, as a stagnant weather pattern settled over most of North America. From June 19th to 21st, temperatures soared into the 30s from southwestern Ontario to New Brunswick, with heat waves (3 or more consecutive days of 32°C or higher) recorded in Windsor, Sarnia and Toronto, and many other cities, such as Kitchener-Waterloo, Hamilton, Peterborough, Ottawa, Montreal and Quebec City, came very close.

The heat continued for the rest of the season, and into the beginning of Autumn, with July ranking as the hottest month ever recorded in Canada. The only regions of the country that didn't see above-average temperatures were along the B.C. and Yukon coastlines. The season also saw the devastating drought in the United States, which also caused record low water levels in the Great Lakes.

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As for this year, be sure to get out and enjoy the weather while you can. What ENSO will be doing this year is still up in the air, so who knows if next year will be another nice summer or a return to soul-crushing heat and drought. The only caution for the months to come is that we may be seeing higher than normal levels of UV radiation, so be sure to wear your sun-screen.

(Images courtesy: Getty, Environment Canada)

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