The early-season summer pattern offers the first clues to summer’s broader themes: Warmth favoured in the West and North, a cooler and more unsettled start in the East. As the Atlantic Ocean continues to warm, the trough is expected to retreat westward through summer. The central question becomes how far west it shifts, and whether it stays centred near the Great Lakes and/or broadens farther west.
The West and North
British Columbia, Yukon, and the Northwest Territories stand out as the strongest warmth signal in the country. That naturally raises concern for:
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Drought
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Early heat
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Elevated wildfire risk
East of the Rockies
Confidence drops when it comes to where the coolest pocket sets up. The biggest uncertainty is whether the trough-heavy pattern focuses:
The most likely place to miss out on summer’s biggest heat may be the middle of the country.
What to look for in the months ahead
How quickly El Niño strengthens: Will it approach 2015 levels?
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Where the summer trough anchors
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Great Lakes versus Prairies
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Early B.C. heat and wildfire starts, including wildfire smoke impacts
So, as the summer signal continues to evolve, the atmosphere should begin to reveal which path Canada is truly taking.
