September Weather in Alliston, Canada

Last updated: June 18, 2025

In Alliston, Canada, the average temperature in September hovers around 16°C (61°F). Expect a range from a chilly minimum of 0°C (33°F) to a warm maximum of 32°C (90°F). During this month, you can anticipate about 68 mm (2.7 in) of precipitation over 9 days, with an average humidity of 74%, making it a unique climate experience!

September Temperature in Alliston

In September in Alliston, the average temperature is 16°C (61°F). Maximums can reach 32°C (90°F), and minimums can be as low as 0°C (33°F). This varied weather makes Alliston an ideal destination for travelers looking to experience a wide range of outdoor activities and enjoy the beautiful scenery.

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

The chart illustrates September temperature patterns in Alliston, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Alliston, September typically has an average temperature of 16°C (61°F), with highs reaching up to 32°C (90°F) and lows dropping to around 0°C (33°F).

Data source: Temperature data for Alliston generated using information from the Copernicus Climate Change Service.

September Precipitation in Alliston

In Alliston in September, the precipitation amount is 68 mm (2.7 in) spread over 9 days.

September Precipitation Trends in Alliston

The chart displays monthly precipitation patterns in Alliston, 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 Alliston, September typically receives around 68 mm (2.7 inches) of precipitation spread over approximately 9 days.

Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.

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Millimeters (mm) Inches (in)

September Humidity in Alliston

In Alliston in September humidity is 74%. With an average temperature of 16°C (61°F), this humidity feels like a damp blanket wrapping around you, making traveling quite uncomfortable as the air feels thick and muggy, potentially leading to fatigue and a longing for a cool breeze.

September Average Humidity in Alliston

This chart illustrates the average monthly humidity levels in Alliston, 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 Alliston is approximately 74%, offering insight into how humid the weather typically is during this month.

Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Alliston

In Alliston 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 Alliston.

Maximum UV Index Levels in Alliston for September

The chart shows the monthly maximum UV Index (UVI) for Alliston 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 Alliston typically reaches 7, which falls under the high exposure category.

Data source: Alliston 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 Alliston Compares to Other Months

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

This table compares monthly weather conditions in Alliston, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	-6°C (21°F)	59 mm (2.3 inches)	93%	low
February Weather	-5°C (23°F)	62 mm (2.5 inches)	94%	moderate
March Weather	-1°C (31°F)	58 mm (2.3 inches)	87%	moderate
April Weather	5°C (42°F)	102 mm (4.0 inches)	82%	very high
May Weather	13°C (55°F)	99 mm (3.9 inches)	74%	very high
June Weather	18°C (65°F)	94 mm (3.7 inches)	68%	very high
July Weather	21°C (71°F)	90 mm (3.5 inches)	67%	very high
August Weather	20°C (69°F)	96 mm (3.8 inches)	67%	very high
September Weather	16°C (61°F)	68 mm (2.7 inches)	74%	high
October Weather	10°C (50°F)	98 mm (3.9 inches)	83%	moderate
November Weather	2°C (36°F)	76 mm (3.0 inches)	89%	moderate
December Weather	-3°C (28°F)	69 mm (2.7 inches)	91%	low