Cooler fall weather forecast to return to Montreal

Much cooler, wet weather is on tap for Montreal as the week progresses. (AccuWeather)

The weather in Montreal this October has been nothing short of spectacular. To date, including Monday, Montreal has recorded 9 days where the temperature has been 21C (70F) or higher. Normally, we have none. The average high temperature between October 1 and 22 was 18.9C (66F), the long-term average for this period should be 13C (55F). The overnight lows have been mild as well, with an average low of 8.6C (48F). The normal low should be 4C (39F). Our peak temperature so far this month was 25.8C (79F). On Monday, the warm weather continued, with a high of 22C (72F) at Trudeau Airport, shy of the daily record of 25C (77F) set in 1979, and well above the normal of 11C (52F). St Anicet, southwest of Montreal, was the warmest location in Canada on Monday, reaching a record-breaking 25C (77F).

There are major changes in the near future. The high pressure responsible for the perfect weekend weather will move off the east coast tonight. In its wake, a low pressure area and cold front will slide across the Great Lakes into southern Quebec on Tuesday. A period of showers and isolated thunderstorms is forecast Tuesday into early Wednesday morning. The rain may be heavy at times, with 25mm (1 inch) expected in Montreal, but as much as 50mm (2 inches) southeast of the city towards Sherbrooke and the US border. Gusty southerly winds up to 60km/h are forecast to accompany the rain on Tuesday. The temperature will be mild once again, reaching 21C (70F) before the frontal passage. Once the front clears the area, cooler air will settle into southern Quebec. The weather will not be frigid, just closer to what is should be for late October. The forecast high on Thursday is expected to be 13C (55F). Temperatures will moderate slightly into the weekend, with the chance of showers, before even colder air arrives to start next week.

Halloween & Beyond
At this time, the Halloween forecast looks cloudy and cooler, but dry in Montreal, with a daytime high of 9C (48F). Expect trick or treating temperatures of around 5C (41F). Looking ahead to the first week of November, single digit daytime high temperatures are expected at this time, along with perhaps a few showers or even some snowflakes. Frost is likely on numerous nights to start November, as temperatures drop below normal for the first time in weeks.