Guernsey weather in September 2025

Expect 18°C daytime maximum temperatures in the shade with on average 6 hours of sunshine per day in Guernsey in September. Check more long-term weather averages for Guernsey in September before you book your next holiday to Guernsey in 2025/2026.

  • 18°C maximum daytime temperature in September in Guernsey (St Peter Port)18
    18°C max day temperature
  • 6 hours of sunshine per day
  • 13 days with some rainfall in September in Guernsey (St Peter Port)13
    13 days with some rainfall
  • 13°C minimum night-time temperature in September in Guernsey (St Peter Port)13
    13°C min night temperature
  • 13 hours of daylight per day in September in Guernsey (St Peter Port)13
    13 hours of daylight per day
  • No heat & humidity in September in Guernsey (St Peter Port)0
    No heat & humidity
  • 63 mm monthly rainfall in September in Guernsey (St Peter Port)63
    63 mm of monthly rainfall
  • UV (maximum) index 4 (Moderate) in September in Guernsey (St Peter Port)4
    4 (Moderate) UV index
  • 17°C sea temperature in September in Guernsey (St Peter Port)17
    17°C sea temperature

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The September weather guide for Guernsey, represented by St Peter Port, (St Peter Port) 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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How hot is it in Guernsey in September?

Daytime temperatures usually reach 18°C in St Peter Port, Guernsey in September, falling to 13°C at night.

How sunny is it in Guernsey in September?

There are normally 6 hours of bright sunshine each day in St Peter Port, Guernsey in September - that's 45% of daylight hours.

How warm is the sea around Guernsey in September?

The average sea temperature around St Peter Port, Guernsey in September is 17°C.

Does it rain in Guernsey in September?

There are usually 13 days with some rain in St Peter Port, Guernsey in September and the average monthly rainfall is 63mm.

Guernsey September sunrise & sunset times

Browse the sunrise and sunset times for Guernsey in September 2025. Select a month to view Guernsey sunrise and sunset times for the next 12 months. The Guernsey sunrise and sunset times shown below are for St Peter Port.

JanFebMarAprMayJunJulAugSepOctNovDec

Date Sunrise times Sunset times
Monday, 1st September 2025 05:26 18:53
Monday, 15th September 2025 05:47 18:23
Tuesday, 30th September 2025 06:09 17:51

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