Cornwall weather

Our guide to the weather in Cornwall during September

17

Average high

4

UV Index

83mm

Monthly rainfall

82%

Humidity

We've looked at the most up-to-date weather data for Cornwall, covering the last 12 years up to 2024, plus we've asked our team of travel bloggers for their first-hand experiences in order to answer the most frequently asked questions about Cornwall weather in September.

What's the temperature like in Cornwall during September?

The temperature is extremely stable in September with average highs of 17℃ and lows just 3℃ lower at 14℃. The UV index will be moderate at this time of year, so not something to worry about for the average person. However, if you're going to be outside for long periods it's worth wearing a broad spectrum SPF 30+ sunscreen and UV-blocking sunglasses. Remember that bright surfaces, such as water and sand increase UV exposure.

Does it rain in Cornwall during September?

On average, there will be 5 rainy days during the month, amounting to 83.4mm in total. That's a significant amount of rain. For comparison, the wettest months in the UK typically sees between 80mm and 100mm, depending on where you are. You're not likely to see a thunderstorm during your trip.

Is it windy in Cornwall during September?

Expect moderate breeze becoming stronger at times during September, with occasional gusts up to 20mph. With moderate air temperatures, any breeze will feel cool.

Hotel stays in Cornwall

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Weather in Cornwall

Our month-by-month guide to the weather and climate in Cornwall

9.2

Cornwall weather in

January
9.0

Cornwall weather in

February
9.9

Cornwall weather in

March
11.4

Cornwall weather in

April
13.5

Cornwall weather in

May
16.1

Cornwall weather in

June
18.1

Cornwall weather in

July
18.2

Cornwall weather in

August
16.9

Cornwall weather in

September
14.8

Cornwall weather in

October
12.0

Cornwall weather in

November
10.3

Cornwall weather in

December