Caernarfon weather in September 2025

Expect daytime maximum temperatures of 16°C in Caernarfon in September based on long-term weather averages. There are 4 hours of sunshine per day on average with 16 days with some rainfall and typically 141 mm of rainfall in the month.

  • 16°C maximum daytime temperature in September in Caernarfon16
    16°C max day temperature
  • 4 hours of sunshine per day
  • 16 days with some rainfall in September in Caernarfon16
    16 days with some rainfall
  • 10°C minimum night-time temperature in September in Caernarfon10
    10°C min night temperature
  • 13 hours of daylight per day in September in Caernarfon13
    13 hours of daylight per day
  • No heat & humidity in September in Caernarfon0
    No heat & humidity
  • 141 mm monthly rainfall in September in Caernarfon141
    141 mm of monthly rainfall
  • UV (maximum) index 4 (Moderate) in September in Caernarfon4
    4 (Moderate) UV index
  • 15°C sea temperature in September in Caernarfon15
    15°C sea temperature

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The September weather guide for Wales (Caernarfon) 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 Caernarfon in September?

Daytime temperatures usually reach 16°C in Caernarfon in September, falling to 10°C at night.

How sunny is it in Caernarfon in September?

There are normally 4 hours of bright sunshine each day in Caernarfon in September - that's 32% of daylight hours.

How warm is the sea around Caernarfon in September?

The average sea temperature around Caernarfon in September is 15°C.

Does it rain in Caernarfon in September?

There are usually 16 days with some rain in Caernarfon in September and the average monthly rainfall is 141mm.

Caernarfon September sunrise & sunset times

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

JanFebMarAprMayJunJulAugSepOctNovDec

Date Sunrise times Sunset times
Monday, 1st September 2025 05:27 19:06
Monday, 15th September 2025 05:51 18:32
Tuesday, 30th September 2025 06:17 17:56

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