Cornwall (St Ives)
September
Weather in Cornwall for September 2025
Your guide to Cornwall weather in September - trends and predictions
In general, the average temperature in Cornwall at the beginning of September is 16.1 °C. As the month progressed, temperatures tended to moderately fall, reaching an average of 14.4 °C by the end of September.
Cornwall in September brings notable rainfall, with an average of 18 rainy days and a total precipitation of 120.3 mm.
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Temperatures
Rain 🌧️
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12
Dry days
18
Rainy days
0
Snow days
16°/13°
Temperatures
30 km/h
Avg max wind
80 %
Avg humidity
Cornwall Weather September
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| Mon. | Tue. | Wed. | Thu. | Fri. | Sat. | Sun. |
|---|---|---|---|---|---|---|
| 1  19° | 2  17° | 3 16° | 4 14° | 5 15° | 6  16° | 7 16° |
| 8 17° | 9 14° | 10 16° | 11  14° | 12 13° | 13  14° | 14  15° |
| 15 16° | 16 18° | 17 17° | 18 19° | 19 20° | 20 18° | 21  17° |
| 22 16° | 23 16° | 24 15° | 25 16° | 26  14° | 27 12° | 28 13° |
| 29 16° | 30 15° |
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Temperatures trend during September in Cornwall
See the weather trend as well as the moving average line
September weather day by day
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| Date | Weather | Temperatures | Rain | UV | More |
|---|---|---|---|---|---|
| 1 Sept. | Cloudy | 19° /15° | 0 mm | 4 | |
| 2 Sept. | Patchy rain possible | 17° /14° | 0.9 mm | 4 | |
| 3 Sept. | Patchy rain possible | 16° /14° | 0.2 mm | 4 | |
| 4 Sept. | Patchy rain possible | 14° /12° | 1.5 mm | 3 | |
| 5 Sept. | Light rain shower | 15° /12° | 16.6 mm | 4 | |
| 6 Sept. | Moderate rain | 16° /14° | 19.9 mm | 4 | |
| 7 Sept. | Patchy rain possible | 16° /14° | 1.5 mm | 4 | |
| 8 Sept. | Light rain shower | 17° /15° | 0.8 mm | 4 | |
| 9 Sept. | Cloudy | 14° /13° | 0 mm | 3 | |
| 10 Sept. | Light rain shower | 16° /13° | 1.7 mm | 4 | |
| 11 Sept. | Patchy light drizzle | 14° /12° | 1.2 mm | 3 | |
| 12 Sept. | Patchy rain possible | 13° /11° | 1.5 mm | 3 | |
| 13 Sept. | Partly cloudy | 14° /12° | 0.1 mm | 4 | |
| 14 Sept. | Sunny | 15° /11° | 0 mm | 5 | |
| 15 Sept. | Cloudy | 16° /13° | 0 mm | 4 | |
| 16 Sept. | Patchy rain possible | 18° /13° | 0.2 mm | 4 | |
| 17 Sept. | Sunny | 17° /12° | 0 mm | 5 | |
| 18 Sept. | Sunny | 19° /13° | 0 mm | 5 | |
| 19 Sept. | Sunny | 20° /14° | 0 mm | 6 | |
| 20 Sept. | Light rain shower | 18° /14° | 3.3 mm | 4 | |
| 21 Sept. | Patchy light rain with thunder | 17° /13° | 10.8 mm | 4 | |
| 22 Sept. | Light rain shower | 16° /14° | 6.6 mm | 4 | |
| 23 Sept. | Light rain shower | 16° /14° | 4.9 mm | 4 | |
| 24 Sept. | Patchy rain possible | 15° /13° | 0.3 mm | 4 | |
| 25 Sept. | Light rain shower | 16° /12° | 7.3 mm | 4 | |
| 26 Sept. | Moderate or heavy rain with thunder | 14° /12° | 21.5 mm | 3 | |
| 27 Sept. | Light rain shower | 12° /11° | 5.5 mm | 3 | |
| 28 Sept. | Patchy rain possible | 13° /10° | 0.2 mm | 3 | |
| 29 Sept. | Light rain shower | 16° /11° | 12.7 mm | 4 | |
| 30 Sept. | Light rain shower | 15° /13° | 1.1 mm | 4 | |
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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.
Cornwall in September - FAQ
What are the expected maximum and minimum temperatures in Cornwall during September?
Enjoy moderate daytime temperatures of up to 16° and cooler nights around 13°. 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 120.3 mm is expected in Cornwall during September, occurring over more than 18 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 30 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 💧
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