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September Weather in Montreal, United States

Last updated: June 24, 2025

In September, the average temperature in Montreal, United States hovers around 15°C (60°F), with the mercury dipping as low as 1°C (34°F) and reaching up to a warm 32°C (89°F). Visitors should prepare for 94 mm (3.7 in) of precipitation spread over 13 days, while the air maintains an average humidity of 73%. Make sure to pack accordingly for a blend of pleasant warmth and refreshing rain!

September Temperature in Montreal

In September in Montreal, the average temperature is 15°C (60°F). The maximum can reach 32°C (89°F) and the minimum can be as low as 1°C (34°F). Be prepared for a wide range of temperatures when traveling to Montreal this month.

September Weather in Montreal: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Montreal, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Montreal, September typically has an average temperature of 15°C (60°F), with highs reaching up to 32°C (89°F) and lows dropping to around 1°C (34°F).
JanFebMarAprMayJunJulAugSepOctNovDec161528385465706660463122
Data source: Temperature data for Montreal generated using information from the Copernicus Climate Change Service.
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The average of daily temperatures (24 hours) calculated across all days in the month.

September Precipitation in Montreal

In Montreal in September, the precipitation amount is 94 mm (3.7 in) spread over 13 days.

September Precipitation Trends in Montreal

The chart displays monthly precipitation patterns in Montreal, with values for each month alongside September’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how September’s conditions compare to those of other months. In Montreal, September typically receives around 94 mm (3.7 inches) of precipitation spread over approximately 13 days.
JanFebMarAprMayJunJulAugSepOctNovDec395252878711187110941126174
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Montreal

In Montreal in September, humidity is 73%. With an average temperature of 15°C (60°F), this humidity feels like a warm, sticky embrace that can make traveling feel quite muggy; therefore, staying hydrated and taking breaks in shaded areas is essential to fully enjoy your adventure.

September Average Humidity in Montreal

This chart illustrates the average monthly humidity levels in Montreal, with September’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In September, average humidity in Montreal is approximately 73%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec93%93%89%85%76%71%70%71%73%82%88%91%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Montreal

In Montreal in September, the maximum UV index is 7, which corresponds to the high Exposure Category. This means that the time to burn is approximately 25 minutes. For more detailed information, you can check the Hourly UV Index in Montreal.

Maximum UV Index Levels in Montreal for September

The chart shows the monthly maximum UV Index (UVI) for Montreal in September, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues. In September, the maximum UV index in Montreal typically reaches 7, which falls under the high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec2458810987532
Data source: Montreal September UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

  •  Extreme (11+): Avoid the sun, stay in shade.
  •  Very High (8-10): Limit sun exposure.
  •  High (6-7): Use SPF 30+ and protective clothing.
  •  Moderate (3-5): Midday shade recommended.
  •  Low (0-2): No protection needed.

How September Weather in Montreal Compares to Other Months

Weather in Montreal varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Montreal, focusing on differences in temperature, rainfall, humidity, and UV levels.

This table compares monthly weather conditions in Montreal, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-9°C (16°F)39 mm (1.5 inches)93%low
February Weather-9°C (16°F)52 mm (2.1 inches)93%moderate
March Weather-2°C (28°F)52 mm (2.0 inches)89%moderate
April Weather3°C (38°F)87 mm (3.4 inches)85%very high
May Weather12°C (54°F)87 mm (3.4 inches)76%very high
June Weather18°C (65°F)111 mm (4.4 inches)71%very high
July Weather21°C (70°F)87 mm (3.4 inches)70%very high
August Weather19°C (67°F)110 mm (4.3 inches)71%very high
September Weather15°C (60°F)94 mm (3.7 inches)73%high
October Weather8°C (46°F)112 mm (4.4 inches)81%moderate
November Weather-1°C (31°F)61 mm (2.4 inches)87%moderate
December Weather-6°C (22°F)74 mm (2.9 inches)91%low

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