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Weather in St. Catharines for September 2025

Your guide to St. Catharines weather in September - trends and predictions

    Temperatures

  • Until now, September 2025 in St. Catharines is slightly cooler than the historical average by -1.3 °C.

  • Expect cooler weather in the next days in St. Catharines with the forecast suggesting a temperature of 19.9 °C, lower than the historical average.

  • In general, the average temperature in St. Catharines at the beginning of September is 24.4 °C. As the month progressed, temperatures tended to significantly cool down, reaching an average of 17.7 °C by the end of September.

    • Rain 🌧️

  • With an average of 5 rainy days, St. Catharines experiences minimal rainfall in September.

    • More

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

Average dry days
25
Dry days
Average rainy days
5
Rainy days
Average snowy days
0
Snow days
Average temperatures
22°/15°
Temperatures
Average wind speed
20 km/h
Avg max wind
Average humidity
74 %
Avg humidity

St. Catharines Weather September

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

Temperatures trend during September in St. Catharines

See the weather trend as well as the moving average line

September weather in St. Catharines day by day

Click on a date for more information
August October
Date Weather Temperatures Rain UV More
1 Sept. Mist
Mist
 23° /14° 0.3 mm 5
2 Sept. Mist
Mist
 23° /14° 0.2 mm 5
3 Sept. Thundery outbreaks possible
Thundery outbreaks possible
 26° /14° 0 mm 6
4 Sept. Partly cloudy
Partly cloudy
 25° /16° 5 mm 6
5 Sept. Partly cloudy
Partly cloudy
 27° /15° 0 mm 7
6 Sept. Overcast
Overcast
 26° /16° 0.5 mm 6
7 Sept. Light rain shower
Light rain shower
 21° /14° 3.2 mm 5
8 Sept. Mist
Mist
 20° /13° 0 mm 5
9 Sept. Overcast
Overcast
 23° /13° 0.3 mm 6
10 Sept. Overcast
Overcast
 20° /15° 0.3 mm 5
11 Sept. Overcast
Overcast
 23° /15° 0 mm 5
12 Sept. Mist
Mist
 24° /15° 0.4 mm 5
13 Sept. Overcast
Overcast
 22° /14° 0 mm 5
14 Sept. Partly cloudy
Partly cloudy
 22° /13° 0 mm 1.3
15 Sept. Partly cloudy
Partly cloudy
 23° /13° 0 mm 1.3
16 Sept. Partly cloudy
Partly cloudy
 23° /14° 0 mm 1.3
17 Sept. Cloudy
Cloudy
 23° /13° 0 mm 1.3
18 Sept. Sunny
Sunny
 26° /17° 0 mm 0
19 Sept. Sunny
Sunny
 19° /14° 0 mm 5
20 Sept. Sunny
Sunny
 19° /10° 0 mm 4
21 Sept. Sunny
Sunny
 19° /13° 0 mm 5
22 Sept. Patchy rain possible
Patchy rain possible
 20° /16° 2.2 mm 4
23 Sept. Patchy rain possible
Patchy rain possible
 20° /17° 4 mm 4
24 Sept. Patchy rain possible
Patchy rain possible
 20° /17° 2.7 mm 4
25 Sept. Moderate rain
Moderate rain
 18° /16° 6.9 mm 4
26 Sept. Sunny
Sunny
 13° /11° 0 mm 4
27 Sept. Sunny
Sunny
 13° /9° 0 mm 4
28 Sept. Patchy rain possible
Patchy rain possible
 19° /13° 1.9 mm 5
29 Sept. Overcast
Overcast
 21° /16° 0 mm 5
30 Sept. Mist
Mist
 20° /14° 0 mm 5
Next
Important Notice
Our weather forecast for St. Catharines 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 St. Catharines forecast closer to your planned date for the most up-to-date weather information.
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St. Catharines in September - FAQ

What are the expected maximum and minimum temperatures in St. Catharines during September?
During September, expect a variety of temperatures with highs around 22° and lows near 15°, suitable for diverse activities and preferences.
How much rainfall should be expected in St. Catharines during September?
In September, St. Catharines can expect light to moderate rainfall, totaling 22.4 mm across approximately 5 days. Occasional showers are possible, and planning ahead for them could be helpful.
What are the typical wind conditions in St. Catharines during September?
The average wind speed in St. Catharines during September is 20 km/h, suggesting breezy to windy conditions, depending on your activities.

September rainfall patterns in St. Catharines

Explore the daily rainfall trends and prepare for St. Cathariness September weather 💧

UV exposure in St. Catharines during September

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

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Get accurate weather forecasts for St. Catharines, located at latitude 43.171 and longitude -79.243. Stay updated with localized weather information tailored for St. Catharines.

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