Since 1942 there has been some warming in August temperatures in Montreal. For example, some years like 2021 show deviations of up to 3°C above normal. Current forecasts are for the month to end 1-1.5°C above normal, suggesting multiple heat scenarios for September.
Possible heat in September
While August was one of the ten warmest months with more than 1.4 °C above normal, the following September was more often warm than cool. Overall, only two out of ten September months turned out to be cool.
For the months of August, which are not hot enough to be in the top 10 but still have temperatures above normal of up to 1.3°C, we observe the same trend: September is generally rather warm . Only four out of fifteen months of September were cool.
The rain could also be part of it
When it comes to rain, September tends to be dry after a much warmer than normal August, with a ratio of three dry to six normal and one rainy. Conversely, September tends to rain more after a slightly warmer than normal August, which could be the case for 2022. So there are seven rainy, five normal and three dry.
The month of August 2021, an emblematic case of this trend, was particularly hot and even the hottest on record. The following September was warmer than normal but with normal rainfall. As a reminder, a month of September that qualifies as normal has average high temperatures of 21°C in southern Quebec, including 7 days when the temperature reaches 25°C or more.
