Cornwall (St Ives)
September
Weather in Cornwall for September 2027
Your guide to Cornwall weather in September - trends and predictions
In general, the average temperature in Cornwall at the beginning of September is 17.3 °C. As the month progressed, temperatures tended to moderately fall, reaching an average of 15.6 °C by the end of September.
Cornwall in September brings notable rainfall, with an average of 16 rainy days and a total precipitation of 107.8 mm.
Is September a good time to visit Cornwall? check out the best time to travel to Cornwall page.
✨ Is September a good time to visit Cornwall? – Ask the AI Weatherman
Temperatures
Rain 🌧️
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14
Dry days
16
Rainy days
0
Snow days
16°/13°
Temperatures
30 km/h
Avg max wind
81 %
Avg humidity
Cornwall Weather September
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Temperatures trend during September in Cornwall
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September weather in Cornwall day by day
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| Date | Weather | Temperatures | Rain | UV | More |
|---|---|---|---|---|---|
| 1 Sept. |  Light rain | 18° /15° | 3.4 mm | 3 | |
| 2 Sept. | Light rain | 18° /14° | 3.9 mm | 3 | |
| 3 Sept. | Light rain | 18° /15° | 4.7 mm | 3 | |
| 4 Sept. | Light rain | 16° /13° | 3.5 mm | 3 | |
| 5 Sept. | Light rain | 17° /13° | 5.6 mm | 4 | |
| 6 Sept. |  Moderate rain | 18° /14° | 6.9 mm | 4 | |
| 7 Sept. | Light rain | 17° /14° | 3.1 mm | 3 | |
| 8 Sept. | Light rain | 16° /13° | 7.3 mm | 3 | |
| 9 Sept. | Light rain | 15° /13° | 5.6 mm | 3 | |
| 10 Sept. | Light rain | 17° /14° | 2.5 mm | 3 | |
| 11 Sept. | Patchy light drizzle | 16° /13° | 2.1 mm | 3 | |
| 12 Sept. | Light rain | 16° /13° | 4 mm | 3 | |
| 13 Sept. |  Patchy rain possible | 16° /14° | 2.1 mm | 3 | |
| 14 Sept. | Patchy rain possible | 17° /14° | 2.3 mm | 4 | |
| 15 Sept. | Patchy rain possible | 16° /14° | 2 mm | 3 | |
| 16 Sept. | Patchy rain possible | 16° /13° | 1.4 mm | 3 | |
| 17 Sept. | Patchy rain possible | 17° /14° | 1.3 mm | 3 | |
| 18 Sept. |  Sunny | 18° /14° | 0.4 mm | 3 | |
| 19 Sept. | Patchy rain possible | 18° /15° | 1.1 mm | 4 | |
| 20 Sept. | Light rain | 17° /14° | 6.5 mm | 3 | |
| 21 Sept. |  Patchy light rain with thunder | 16° /13° | 7.7 mm | 3 | |
| 22 Sept. | Light rain shower | 16° /13° | 2.3 mm | 3 | |
| 23 Sept. | Light rain shower | 15° /12° | 1.8 mm | 3 | |
| 24 Sept. | Patchy rain possible | 16° /12° | 0.1 mm | 3 | |
| 25 Sept. | Light rain | 16° /12° | 2.5 mm | 3 | |
| 26 Sept. |  Moderate or heavy rain with thunder | 15° /12° | 7.5 mm | 3 | |
| 27 Sept. | Light rain | 14° /12° | 4.3 mm | 2 | |
| 28 Sept. | Patchy rain possible | 15° /11° | 0.1 mm | 3 | |
| 29 Sept. | Light rain | 17° /12° | 8.4 mm | 3 | |
| 30 Sept. | Light rain | 15° /12° | 3.5 mm | 3 | |
| 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.
Change Month
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 107.8 mm is expected in Cornwall during September, occurring over more than 16 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.
Cornwall water temperatures in September
The average water temperature of the Atlantic Ocean near Cornwall in September is 15.3 °C. At the beginning of September temperatures are around 15.5 °C; by the end of the month they stay fairly steady and reach 15.1 °C.
- What is the water temperature in Cornwall in September?
- The average water temperature in Cornwall in September is 15.3 °C.
- Can you swim in Cornwall in September?
- Brisk: quick dips and active swimming are fine, but pack a 2–3 mm spring suit if you plan longer sessions or early-morning outings.
September rainfall patterns in Cornwall
Explore the daily rainfall trends and prepare for Cornwalls September weather 💧
Typically, Cornwall has 16 rainy days in September with a total of 107.8 mm of rainfall.
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