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Weather in Cornwall for September 2025

Your guide to Cornwall weather in September - trends and predictions

    Temperatures

  • Until now, September 2025 in Cornwall is slightly cooler than the historical average by -0.8 °C.

  • Expect cooler weather in the next days in Cornwall with the forecast suggesting a temperature of 21.6 °C, lower than the historical average.

  • In general, the average temperature in Cornwall at the beginning of September is 25.1 °C. As the month progressed, temperatures tended to significantly cool down, reaching an average of 18.4 °C by the end of September.

    • Rain 🌧️

  • Cornwall experiences moderate rainfall in September, with an average of 8 rainy days and a total precipitation of 96.5 mm.

    • More

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Average dry days
22
Dry days
Average rainy days
8
Rainy days
Average snowy days
0
Snow days
Average temperatures
22°/11°
Temperatures
Average wind speed
13 km/h
Avg max wind
Average humidity
77 %
Avg humidity

Cornwall Weather September

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

Temperatures trend during September in Cornwall

See the weather trend as well as the moving average line

September weather in Cornwall day by day

Click on a date for more information
August October
Date Weather Temperatures Rain UV More
1 Sept. Mist
Mist
 26° /10° 2.4 mm 6
2 Sept. Partly cloudy
Partly cloudy
 23° /11° 0 mm 6
3 Sept. Overcast
Overcast
 24° /12° 0 mm 6
4 Sept. Patchy rain possible
Patchy rain possible
 27° /14° 17 mm 6
5 Sept. Mist
Mist
 27° /13° 0 mm 6
6 Sept. Sunny
Sunny
 26° /15° 6.8 mm 6
7 Sept. Moderate or heavy rain shower
Moderate or heavy rain shower
 23° /12° 6 mm 5
8 Sept. Light rain shower
Light rain shower
 20° /10° 1.5 mm 4
9 Sept. Cloudy
Cloudy
 22° /8° 0.3 mm 5
10 Sept. Sunny
Sunny
 22° /9° 1.4 mm 6
11 Sept. Fog
Fog
 23° /11° 0.8 mm 5
12 Sept. Partly cloudy
Partly cloudy
 24° /11° 0.1 mm 6
13 Sept. Light rain
Light rain
 20° /11° 4.9 mm 5
14 Sept. Cloudy
Cloudy
 25° /12° 0 mm 1.2
15 Sept. Partly cloudy
Partly cloudy
 25° /13° 0 mm 1.3
16 Sept. Fog
Fog
 24° /8° 0 mm 1.2
17 Sept. Cloudy
Cloudy
 28° /10° 0 mm 1.2
18 Sept. Patchy rain possible
Patchy rain possible
 30° /14° 2.9 mm 0
19 Sept. Partly cloudy
Partly cloudy
 17° /7° 0.1 mm 4
20 Sept. Sunny
Sunny
 20° /4° 0 mm 4
21 Sept. Sunny
Sunny
 24° /5° 0 mm 4
22 Sept. Sunny
Sunny
 27° /12° 0 mm 5
23 Sept. Patchy rain possible
Patchy rain possible
 18° /14° 4 mm 4
24 Sept. Patchy rain possible
Patchy rain possible
 17° /16° 4.3 mm 4
25 Sept. Patchy rain possible
Patchy rain possible
 21° /10° 0.3 mm 4
26 Sept. Sunny
Sunny
 12° /4° 0 mm 3
27 Sept. Sunny
Sunny
 15° /3° 0 mm 3
28 Sept. Mist
Mist
 21° /9° 0 mm 5
29 Sept. Cloudy
Cloudy
 21° /10° 0 mm 5
30 Sept. Mist
Mist
 22° /12° 0 mm 5
Next
Important Notice
Our weather forecast for Cornwall 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 Cornwall forecast closer to your planned date for the most up-to-date weather information.
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Cornwall in September - FAQ

What are the expected maximum and minimum temperatures in Cornwall during September?
Enjoy moderate daytime temperatures of up to 22° and cooler nights around 11°. Ideal for a range of outdoor activities, from hiking to city tours.
How much rainfall should be expected in Cornwall during September?
Moderate rainfall is anticipated in Cornwall during September, with a total of 96.5 mm spread over approximately 8 days. Considering plans for rainy days is advisable.
What are the typical wind conditions in Cornwall during September?
The average wind speed in Cornwall during September is 13 km/h, suggesting breezy to windy conditions, depending on your activities.

September rainfall patterns in Cornwall

Explore the daily rainfall trends and prepare for Cornwalls September weather 💧

UV exposure in Cornwall during September

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

Quick links

More Cornwall weather pages
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Location coordinates Where is Cornwall?

Get accurate weather forecasts for Cornwall, located at latitude 45.018 and longitude -74.728. Stay updated with localized weather information tailored for Cornwall.

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