The federal forecast compares June–August 2026 to the 1991–2020 climate baseline and concludes that most of Canada faces a high likelihood of above-normal temperatures. According to a Global News report on the Environment and Climate Change Canada outlook, the strongest warm signals are concentrated in British Columbia, Yukon, the mainland Northwest Territories and Nunavut, the northern Prairies, and Atlantic Canada. Ontario is also warm, but it does not carry the same exceptional anomaly as the western and Atlantic regions.
Seasonal outlooks describe odds, not certainties. ClimateData.ca's primer on how ECCC seasonal forecasts work clarifies that the maps indicate the probability that a seasonal average will land above, near, or below normal relative to the long-term climate. That nuance matters. ECCC meteorologist Jennifer Smith emphasized to Global News that day-to-day weather will still be shaped by cold fronts, thunderstorms, and onshore breezes, so cooler interludes can still occur inside an overall hotter-than-normal season. A cool weekend in July will not invalidate the forecast — and it will not lower the cumulative load on a home that is unprepared for the rest of the season.
Two climate drivers underpin the outlook. The first is the long warming trend in the Canadian baseline itself — ECCC research scientist Nathan Gillett told Global News that average Canadian summer temperatures have already risen about 1.65 °C since 1948, with Canada warming at nearly twice the global rate. The second is an earlier-than-usual and particularly strong El Niño, which is expected to add extra heat across southern Canada specifically. Together, these two forces push the seasonal odds heavily toward the warm side of normal.
Why Humidity Is Doing Some of the Work
The outlook is not just about temperature. ECCC's projections also show increased odds of higher-than-normal specific humidity, which keeps overnight temperatures from cooling off and makes muggy days feel worse. Meteorologist Peter Quinlan told Global News that nighttime temperatures are trending upward and that, without air conditioning, refreshing indoor temperatures by opening windows at night will be harder than in a typical year — particularly in humid regions near large water bodies in southern Ontario, Quebec, and Atlantic Canada. Even British Columbia, normally drier in summer, is expected to feel stickier than usual. For homes that rely on passive nighttime cooling, that is a real efficiency loss.