Isles of Scilly weather in September
Temperature, sea and sunshine in September: long-term averages from 30 years of weather data, not a forecast.
Holiday weather in September
Poor
Best time to visit: May – August
What is the weather like in Isles of Scilly in September?
In September, Isles of Scilly is mild: daytime highs average 16 °C, and nights cool down to about 15 °C. The sea averages 16.2 °C – swimming is only for the hardy. Expect around 6 hours of sunshine a day. Rain is frequent, with about 10 rainy days and 59 mm in total. It is often windy, with gusts of around 34 km/h. All in all, September is not an ideal month for a holiday in Isles of Scilly.
September compared
How the weather changes from August to October. Tap a month to open it.
| AugustAug | SeptemberSep | OctoberOct | |
|---|---|---|---|
| Score | 25 | 21 | 8 |
| Day | 17° | 16° | 14° |
| Night | 16° | 15° | 13° |
| Sea | 17° | 16° | 14° |
| Sun | 7 h | 6 h | 4 h |
| Rain days | 10 | 10 | 14 |
More details for September
- Daylight
- 12 h 42 min06:59 – 19:42
- UV index
- 4 · moderateclear sky, noon (estimate)All months
- Muggy days
- 0 daysdew point 18 °C or moreAll months
- Wind
- 34 km/haverage daily peakAll months
- Cloud cover
- 64 %on averageAll months
- Hot days
- 0 days30 °C or more
- Time zone
- UTC+1Europe/London
How the score comes together
- Temperatureweight 35 %0 %
- Seaweight 25 %0 %
- Sunshineweight 20 %47 %
- Few rainy daysweight 20 %59 %
Each factor is rated from 0 to 100 % and weighted for the travel style “Sun, sea & sand”.
What to pack in September
- Sunscreen
- A jumper for the evenings
- Rain jacket or umbrella
- Windproof jacket
Isles of Scilly in September: quick answers
Is Isles of Scilly hot in September?
No. In September, Isles of Scilly is mild: daytime highs average 16 °C and nights drop to about 15 °C.
Can you swim in Isles of Scilly in September?
Only if you don't mind cold water: in September the sea averages just 16.2 °C. Comfortable swimming temperatures are not reached at any time of year.
Does it rain much in Isles of Scilly in September?
Rain is frequent, with about 10 rainy days and 59 mm in total.
Isles of Scilly month by month
The whole year in Isles of ScillyAll destinations: United KingdomWhere to go in SeptemberSea temperature in September
Climate averages 1996–2025, not a forecast. Data: Copernicus ERA5 / ERA5-Land via Open-Meteo.com (CC BY 4.0), NOAA OISST, WMO 1991–2020 (NOAA NCEI), GeoNames (CC BY 4.0). Sources & licences