Montreal weather in September
Long-run climate averages for Montreal, Quebec in September, plus what the forecast models say for the days ahead.
In September, Montreal averages 21°C by day and 12°C at night. The wettest month is usually August.
September in Montreal averages a daytime high of 21°C and an overnight low of 12°C, which reads as mild for this part of the world. Across the whole year Montreal sees roughly 1229 mm of precipitation.
Climate averages tell you what to pack. They do not tell you what next Tuesday looks like - for that, see the live Montreal forecast with every model compared and how much they currently agree.
Montreal weather by month
what to expect in Montreal through the yearHere is Montreal's typical weather in each month: the average daytime high and overnight low in °C, how each month feels, and the wettest month marked. Use it to plan any trip to Montreal by season.
Bottom line: over the last 30 days the European model has been the most accurate forecast for Montreal, scoring 94/100 on our CheckWeather Score, ahead of the Env. Canada at 85. See the full CA accuracy scoreboard for exactly how every model is tested.
Common questions
How warm is Montreal in September?
Is September a good time to visit Montreal?
Does it rain a lot in Montreal in September?
Climate averages from ERA5 reanalysis. Model accuracy re-scored over a rolling 30 days. Page updated .