Welcome to Meteorological Fall

Fall weather can be spectacular in Montreal, but it still means less daylight and cooler nights. While many prefer fall, I am already missing the hot weather.

Hard to believe it, but summer 2020 is quickly slipping away, with fall weather on the horizon for Montreal. September 1st is considered the start of meteorological fall, with the warmest three months of the year now behind us. The calendar will catch up in a few weeks on September 22 at 9:31 EDT. There is already a hint of colour in some of the trees in my neighbourhood.

August was a little surprising to me, I had expected it to be just as torrid a month as July. Temperatures were warm to start the month, but much cooler to end. August turned out to be a very humid month, along with frequent rounds of showers and thunderstorms. Those showers and storms not only helped lower the monthly average temperature, but deposited plenty of rainfall. A total of 174.2mm of rain fell at the airport, the normal should be 94.1mm. That total was more than May, June and July combined in Montreal, when just 167.4mm fell. A large amount of the monthly total occurred when the remains of hurricane Isaias passed through southern Quebec on August 4.

All that cloud cover and rainfall resulted in monthly temperatures that were fairly close to normal. The average high at Trudeau Airport was 20.6C (69F), just slightly above the long-term normal of 20.1C (68.2F). There was only 1 day that officially went above 30C at Trudeau, that was 33.2C (91.8C) on August 11. That brings the total number of days at 30C or warmer to a record-setting 24 for Montreal in 2020. 

Looking ahead, September is expected to be slightly warmer than normal, with daily highs in the low to middle 20s. The nights are becoming longer and thus much cooler. The average overnight low starts the month at 12C (54F) but drops into the single digits by the end, at 7C (45F). Frost typically holds off until mid-October, at least in the urban areas.