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Weather in Cornwall for September 2026

Your guide to Cornwall weather in September - trends and predictions

    Temperatures

  • Until now, September 2026 in Cornwall is slightly cooler than the historical average by 0.9 °C.

  • Expect cooler weather in the next days in Cornwall with the forecast suggesting a temperature of 19.6 °C, lower than the historical average.

  • In general, the average temperature in Cornwall at the beginning of September is 24.7 °C. As the month progressed, temperatures tended to significantly cool down, reaching an average of 20.6 °C by the end of September.

    • Rain 🌧️

  • Cornwall experiences moderate rainfall in September, with an average of 10 rainy days and a total precipitation of 137.5 mm.

    • More

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Average dry days
20
Dry days
Average rainy days
10
Rainy days
Average snowy days
0
Snow days
Average temperatures
22°/11°
Temperatures
Average wind speed
13 km/h
Avg max wind
Average humidity
74 %
Avg humidity

Cornwall Weather September

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

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
 25° /11° 22.3 mm 5
2 Sept. Patchy rain possible
Patchy rain possible
 24° /12° 2.1 mm 5
3 Sept. Overcast
Overcast
 25° /14° 53.1 mm 5
4 Sept. Sunny
Sunny
 26° /14° 12.8 mm 6
5 Sept. Sunny
Sunny
 25° /13° 0.2 mm 6
6 Sept. Sunny
Sunny
 25° /14° 5.1 mm 7
7 Sept. Moderate or heavy rain shower
Moderate or heavy rain shower
 23° /12° 4.5 mm 6
8 Sept. Light rain shower
Light rain shower
 20° /11° 5.1 mm 4
9 Sept. Cloudy
Cloudy
 22° /9° 6.6 mm 4
10 Sept. Sunny
Sunny
 22° /10° 1.1 mm 6
11 Sept. Sunny
Sunny
 19° /9° 0 mm 5.4
12 Sept. Overcast
Overcast
 25° /11° 0 mm 5.8
13 Sept. Patchy rain possible
Patchy rain possible
 26° /15° 6.6 mm 3.6
14 Sept. Sunny
Sunny
 17° /9° 0 mm 5
15 Sept. Overcast
Overcast
 20° /7° 11.8 mm 4
16 Sept. Light rain shower
Light rain shower
 22° /16° 9.9 mm 5
17 Sept. Overcast
Overcast
 16° /14° 1.1 mm 4
18 Sept. Mist
Mist
 17° /11° 0.4 mm 5
19 Sept. Sunny
Sunny
 19° /9° 0 mm 5
20 Sept. Sunny
Sunny
 20° /10° 0.5 mm 5
21 Sept. Sunny
Sunny
 22° /11° 0 mm 6
22 Sept. Overcast
Overcast
 21° /12° 1.3 mm 5
23 Sept. Patchy rain possible
Patchy rain possible
 12° /9° 1.1 mm 4
24 Sept. Sunny
Sunny
 19° /9° 0 mm 5
25 Sept. Sunny
Sunny
 18° /11° 67.9 mm 5
26 Sept. Mist
Mist
 21° /11° 24.6 mm 4
27 Sept. Overcast
Overcast
 20° /6° 0 mm 5
28 Sept. Mist
Mist
 22° /11° 0 mm 5
29 Sept. Cloudy
Cloudy
 23° /11° 0 mm 5
30 Sept. Mist
Mist
 21° /11° 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?
Significant rainfall exceeding 137.5 mm is expected in Cornwall during September, occurring over more than 10 days. Preparing for wet conditions is recommended in your planning.

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 💧
Typically, Cornwall has 10 rainy days in September with a total of 137.5 mm of rainfall.

UV exposure in Cornwall during September

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

Quick links

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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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