Swansea weather in September 2025

Expect daytime maximum temperatures of 17°C in Swansea in September based on long-term weather averages. There are 5 hours of sunshine per day on average with 16 days with some rainfall and typically 111 mm of rainfall in the month.

  • 17°C maximum daytime temperature in September in Swansea17
    17°C max day temperature
  • 5 hours of sunshine per day
  • 16 days with some rainfall in September in Swansea16
    16 days with some rainfall
  • 11°C minimum night-time temperature in September in Swansea11
    11°C min night temperature
  • 13 hours of daylight per day in September in Swansea13
    13 hours of daylight per day
  • No heat & humidity in September in Swansea0
    No heat & humidity
  • 111 mm monthly rainfall in September in Swansea111
    111 mm of monthly rainfall
  • UV (maximum) index 4 (Moderate) in September in Swansea4
    4 (Moderate) UV index
  • 17°C sea temperature in September in Swansea17
    17°C sea temperature

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The September weather guide for Wales (Swansea) shows long term weather averages processed from data supplied by CRU (University of East Anglia), the Met Office & the Netherlands Meteorological Institute. Find out more about our data sources.

Metric (°C / mm)  |  Imperial (°F / inches)

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More about Wales

How warm is it in Swansea in September?

Daytime temperatures usually reach 17°C in Swansea in September, falling to 11°C at night.

How sunny is it in Swansea in September?

There are normally 5 hours of bright sunshine each day in Swansea in September - that's 36% of daylight hours.

How warm is the sea around Swansea in September?

The average sea temperature around Swansea in September is 17°C.

Does it rain in Swansea in September?

There are usually 16 days with some rain in Swansea in September and the average monthly rainfall is 111mm.

Swansea September sunrise & sunset times

Browse the sunrise and sunset times for Swansea in September 2025. Select a month to view Swansea sunrise and sunset times for the next 12 months.

JanFebMarAprMayJunJulAugSepOctNovDec

Date Sunrise times Sunset times
Monday, 1st September 2025 05:28 19:02
Monday, 15th September 2025 05:51 18:30
Tuesday, 30th September 2025 06:15 17:55

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