Strong cold front to bring an end to the warm weather in Montreal

A return to reality...

Much cooler, fall weather will return this weekend to southern Quebec. High temperatures on Sunday will only be in the low teens.

Temperatures have been running well-above normal this week across southern Quebec as our warm and dry fall weather persists. The morning low on Thursday was only 16.8C (61F), which established a new record for maximum low temperature that dates back to 1970 (15C). Montreal has had no frost as of today, which places us well behind the last couple of years and certainly short of the average date of October 5. Looking ahead, we should make it to end of the month in the Montreal metro region with no frost or freezing temperatures.

That being said, we will see a dip in the temperatures and a return to more seasonable weather for mid-October. Dirty high pressure has been in control of our weather this week, with plenty of low level moisture, humidity and cloud cover trapped at the surface. The result has been a very warm, but rather gloomy week, with just a few breaks and even some mist or drizzle at times.

Over the next 24 hours a warm front will lift across the region, accompanied by showers. On Saturday, a strong cold will approach the St. Lawrence Valley during the early afternoon, accompanied by steady rain and even a few embedded thunderstorms. At this time rainfall amounts look to be significant, with up to 30mm in Montreal, and locally in excess of 50mm across portions of eastern Ontario and southwestern Quebec. The weather has been a very dry this month, with only 8.2mm of rain to date.

The front will also usher in much colder air. High temperatures will be either side of 21C (70F) today and Saturday, but dip into the single digits by Sunday morning. The high on Sunday and Monday, with lingering clouds and showers will struggle to reach 10C (50F). Overnight lows will return to reality, dropping to 4 to 6C (39 to 43F).

The front will also produce a period of gusty southwest winds on Saturday, backing to the northwest late in the day, between 40 and 60km/h in Montreal.