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Weather in Alliston for September 2026

Your guide to Alliston weather in September - trends and predictions

    Temperatures

  • Until now, September 2026 in Alliston is slightly cooler than the historical average by 1.7 °C.

  • An exceptional deviation from the historical average is forecasted for next days of September 2026 in Alliston with the forecasted temperature being 15.9 °C, much lower than usual.

  • In general, the average temperature in Alliston at the beginning of September is 23.7 °C. As the month progressed, temperatures tended to noticeably cool down, reaching an average of 21.1 °C by the end of September.

    • Rain 🌧️

  • The climate of Alliston in September is notably wet, with an average of 11 rainy days, and a total of 104 mm of precipitation.

    • More

  • New! Chat with our AI weatherman - it’s amazing and free.

Average dry days
19
Dry days
Average rainy days
11
Rainy days
Average snowy days
0
Snow days
Average temperatures
22°/12°
Temperatures
Average wind speed
16 km/h
Avg max wind
Average humidity
74 %
Avg humidity

Alliston Weather September

Move between months or click on a day
August
October
Sun.Mon.Tue.Wed.Thu.Fri.Sat.
1
Partly cloudy
25°
2
Light rain shower
24°
3
Sunny
26°
4
Sunny
24°
5
Sunny
26°
6
Thundery outbreaks possible
22°
7
Light rain shower
19°
8
Overcast
20°
9
Mist
22°
10
Overcast
22°
11
Partly cloudy
23°
12
Heavy rain
24°
13
Overcast
22°
14
Cloudy
22°
15
Mist
23°
16
Partly cloudy
24°
17
Overcast
22°
18
Fog
21°
19
Partly cloudy
20°
20
Sunny
21°
21
Mist
21°
22
Mist
22°
23
Mist
20°
24
Mist
20°
25
Overcast
21°
26
Overcast
21°
27
Overcast
22°
28
Cloudy
18°
29
Overcast
22°
30
Overcast
24°

Temperatures trend during September in Alliston

See the weather trend as well as the moving average line

September weather in Alliston day by day

Click on a date for more information
August October
Date Weather Temperatures Rain UV More
1 Sept. Partly cloudy
Partly cloudy
 25° /13° 0 mm 6
2 Sept. Light rain shower
Light rain shower
 24° /12° 37.7 mm 4
3 Sept. Sunny
Sunny
 26° /13° 0.5 mm 6
4 Sept. Sunny
Sunny
 24° /13° 18.7 mm 6
5 Sept. Sunny
Sunny
 26° /12° 0.9 mm 7
6 Sept. Thundery outbreaks possible
Thundery outbreaks possible
 22° /13° 6.2 mm 5
7 Sept. Light rain shower
Light rain shower
 19° /11° 7.5 mm 4
8 Sept. Overcast
Overcast
 20° /9° 0.2 mm 4
9 Sept. Mist
Mist
 22° /10° 4.6 mm 4
10 Sept. Overcast
Overcast
 22° /11° 0 mm 6
11 Sept. Partly cloudy
Partly cloudy
 23° /11° 0.4 mm 6
12 Sept. Heavy rain
Heavy rain
 24° /13° 7.9 mm 6
13 Sept. Overcast
Overcast
 22° /13° 1.8 mm 5
14 Sept. Cloudy
Cloudy
 22° /11° 0.3 mm 5
15 Sept. Mist
Mist
 23° /11° 2.1 mm 5
16 Sept. Partly cloudy
Partly cloudy
 24° /12° 0 mm 5
17 Sept. Overcast
Overcast
 22° /11° 0.8 mm 5
18 Sept. Fog
Fog
 21° /10° 0 mm 4
19 Sept. Partly cloudy
Partly cloudy
 20° /9° 0 mm 5
20 Sept. Sunny
Sunny
 21° /8° 0 mm 5
21 Sept. Mist
Mist
 21° /10° 2.8 mm 4
22 Sept. Mist
Mist
 22° /11° 12 mm 5
23 Sept. Mist
Mist
 20° /12° 10.6 mm 5
24 Sept. Mist
Mist
 20° /12° 3.7 mm 4
25 Sept. Overcast
Overcast
 21° /12° 4.9 mm 5
26 Sept. Overcast
Overcast
 21° /9° 0 mm 4.5
27 Sept. Overcast
Overcast
 22° /10° 0 mm 4.8
28 Sept. Cloudy
Cloudy
 18° /12° 0 mm 4.8
29 Sept. Overcast
Overcast
 22° /15° 0 mm 4.8
30 Sept. Overcast
Overcast
 24° /13° 5.4 mm 5
Next
Important Notice
Our weather forecast for Alliston in September is based on the analysis of historical data rather than real-time forecast models. While this provides a general overview, weather conditions can change. We recommend that you check the Alliston forecast closer to your planned date for the most up-to-date weather information.
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Alliston in September - FAQ

What are the expected maximum and minimum temperatures in Alliston during September?
Enjoy moderate daytime temperatures of up to 22° and cooler nights around 12°. Ideal for a range of outdoor activities, from hiking to city tours.

How much rainfall should be expected in Alliston during September?
Significant rainfall exceeding 104 mm is expected in Alliston during September, occurring over more than 11 days. Preparing for wet conditions is recommended in your planning.

What are the typical wind conditions in Alliston during September?
The average wind speed in Alliston during September is 16 km/h, suggesting breezy to windy conditions, depending on your activities.

September rainfall patterns in Alliston

Explore the daily rainfall trends and prepare for Allistons September weather 💧
Typically, Alliston has 11 rainy days in September with a total of 104 mm of rainfall.

UV exposure in Alliston during September

Stay informed about UV levels for safe outdoor activities throughout the month of September ☀️

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Location coordinates Where is Alliston?

Get accurate weather forecasts for Alliston, located at latitude 44.15 and longitude -79.866. Stay updated with localized weather information tailored for Alliston.

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