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Weather in Alliston for September 2025

Your guide to Alliston weather in September - trends and predictions

    Temperatures

  • Until now, September 2025 in Alliston has been significantly cooler than historical averages by -2 °C, with average temperature of 21.1 °C.

  • The forecast for the upcoming days in Alliston predicts a temperature of 24.9 °C, which is slightly above the historical average.

  • In general, the average temperature in Alliston at the beginning of September is 23.6 °C. As the month progressed, temperatures tended to slightly increase, reaching an average of 23.7 °C by the end of September.

    • Rain 🌧️

  • Alliston experiences moderate rainfall in September, with an average of 10 rainy days and a total precipitation of 85.8 mm.

    • More

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

Average dry days
20
Dry days
Average rainy days
10
Rainy days
Average snowy days
0
Snow days
Average temperatures
22°/12°
Temperatures
Average wind speed
16 km/h
Avg max wind
Average humidity
73 %
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
23°
2
Light rain shower
22°
3
Partly cloudy
27°
4
Patchy rain possible
25°
5
Partly cloudy
28°
6
Thundery outbreaks possible
22°
7
Light rain shower
18°
8
Overcast
19°
9
Mist
22°
10
Overcast
22°
11
Partly cloudy
24°
12
Heavy rain
24°
13
Overcast
22°
14
Cloudy
24°
15
Mist
24°
16
Partly cloudy
26°
17
Partly cloudy
25°
18
Partly cloudy
26°
19
Partly cloudy
19°
20
Sunny
21°
21
Patchy rain possible
28°
22
Partly cloudy
29°
23
Patchy rain possible
30°
24
Sunny
21°
25
Sunny
22°
26
Sunny
26°
27
Sunny
27°
28
Partly cloudy
25°
29
Mist
25°
30
Mist
20°

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
 23° /11° 0 mm 6
2 Sept. Light rain shower
Light rain shower
 22° /10° 0.2 mm 5
3 Sept. Partly cloudy
Partly cloudy
 27° /13° 0.7 mm 6
4 Sept. Patchy rain possible
Patchy rain possible
 25° /13° 24.9 mm 6
5 Sept. Partly cloudy
Partly cloudy
 28° /12° 0 mm 7
6 Sept. Thundery outbreaks possible
Thundery outbreaks possible
 22° /14° 8.3 mm 5
7 Sept. Light rain shower
Light rain shower
 18° /11° 10 mm 4
8 Sept. Overcast
Overcast
 19° /8° 0.2 mm 5
9 Sept. Mist
Mist
 22° /8° 2.2 mm 5
10 Sept. Overcast
Overcast
 22° /11° 0 mm 5
11 Sept. Partly cloudy
Partly cloudy
 24° /12° 0.6 mm 6
12 Sept. Heavy rain
Heavy rain
 24° /13° 10.5 mm 5
13 Sept. Overcast
Overcast
 22° /13° 0 mm 5
14 Sept. Cloudy
Cloudy
 24° /12° 0 mm 5
15 Sept. Mist
Mist
 24° /11° 0 mm 6
16 Sept. Partly cloudy
Partly cloudy
 26° /12° 0 mm 7
17 Sept. Partly cloudy
Partly cloudy
 25° /11° 0 mm 1.3
18 Sept. Partly cloudy
Partly cloudy
 26° /12° 0 mm 1.2
19 Sept. Partly cloudy
Partly cloudy
 19° /10° 0 mm 1.3
20 Sept. Sunny
Sunny
 21° /5° 0 mm 1.3
21 Sept. Patchy rain possible
Patchy rain possible
 28° /11° 0.9 mm 0
22 Sept. Partly cloudy
Partly cloudy
 29° /17° 0 mm 6
23 Sept. Patchy rain possible
Patchy rain possible
 30° /16° 0.8 mm 5
24 Sept. Sunny
Sunny
 21° /11° 0 mm 5
25 Sept. Sunny
Sunny
 22° /10° 0 mm 4
26 Sept. Sunny
Sunny
 26° /13° 0 mm 5
27 Sept. Sunny
Sunny
 27° /14° 0 mm 5
28 Sept. Partly cloudy
Partly cloudy
 25° /15° 0 mm 5
29 Sept. Mist
Mist
 25° /15° 0 mm 4
30 Sept. Mist
Mist
 20° /12° 0 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?
Moderate rainfall is anticipated in Alliston during September, with a total of 85.8 mm spread over approximately 10 days. Considering plans for rainy days is advisable.
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 💧

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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