Coast to coast, September was a treat of bonus summer warmth
This past month was the warmest September on record for a handful of Canadian cities
The start of fall fell flat for many communities across Canada as summer-like warmth stretched from coast to coast throughout the month of September.
How warm did things get? Water temperatures in the Great Lakes actually warmed up between the start and end of the month.
Canada's October wild card: Record warmth on the table, but snow still in play
Records fall from B.C. to Newfoundland
Persistent stretches of warm days and nights combined to make this past month the warmest September on record for numerous cities across the western half of Canada.
Vancouver’s mean temperature in September came in at 16.8°C. Calgary and Edmonton both rounded out the month with a record-high mean temperature of 16.4°C. Even Banff got in on the unusual toastiness, where the month’s mean temperature topped the heap at 14.1°C.
Back east, St. John’s, Newfoundland, broke the all-time annual record for the most days with a high temperature at or above 20°C. The city saw eight additional readings at or above that magic mark this past September, making for a whopping 81 such days so far in 2025.
Waters also running a fever from coast to coast
Canada found itself surrounded by warmth to round out September.
Water temperatures in the northeastern Pacific and northwestern Atlantic ran 2.0°C to 3.0°C above seasonal for the month of September.
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Hudson Bay, usually the first major body of water to feel the chill, closed the month with water temperatures running as much as 2°C higher than normal.
The Great Lakes are also running a bit of a fever. Lake surface temperatures to start October clocked in at 21.6°C on Lake Erie, 20.0°C on Lake Ontario, and 18.1°C on Lake Huron—all of which are a few degrees above seasonal to start the month.
In fact, September was so warm across the region that overall water temperatures on the Great Lakes increased between Sept. 7 and Oct. 1.
Will the trend continue into October? Be sure to check out our October outlook for the latest on what to expect in your corner of Canada.