First frost of the season on the horizon for Montreal

A frost warning may be required for metro Montreal for Saturday night.

The onset of the cold weather has certainly been slow across eastern Canada this fall. Southern Quebec experienced another mild day on Wednesday, with high temperatures in the middle to upper teens across the region. Trudeau Airport registered a high of 18.2C (65F), well above the long-term average of 11C (52F) for the date. We are already at 13C (55F) Thursday morning. This trend will persist for another day or so before a potent cold front arrives on Friday.

Ahead of that front, we can expect scattered showers Thursday, with a period of steady rain and perhaps a rumble of thunder late tonight and into the wee hours Friday morning.  On Friday, Montreal will have a noticeable change in the airmass, as temperatures drop into the upper single digits by afternoon, along with a gusty west wind up to 40km/h. Clouds will persist with perhaps a sprinkle or two.

Skies will be partly cloudy throughout the weekend, along with seasonable temperatures. If skies clear out completely Saturday night into Sunday morning, there is a very good chance that Montreal will have the first frost of the season. The overnight low is expected to drop to the freezing point in the city and below in the suburbs. The average day of the first frost in Montreal is October 5.

Beyond the weekend, seasonable temperatures are expected next week, with no major storms on the horizon at this point.