Donegal weather in September 2025

Expect 15°C daytime maximum temperatures in the shade with on average 3 hours of sunshine per day in Donegal in September. Check more long-term weather averages for Donegal in September before you book your next holiday to Ireland in 2025/2026.

  • 15°C maximum daytime temperature in September in Donegal15
    15°C max day temperature
  • 3 hours of sunshine per day
  • 22 days with some rainfall in September in Donegal22
    22 days with some rainfall
  • 8°C minimum night-time temperature in September in Donegal8
    8°C min night temperature
  • 13 hours of daylight per day in September in Donegal13
    13 hours of daylight per day
  • No heat & humidity in September in Donegal0
    No heat & humidity
  • 145 mm monthly rainfall in September in Donegal145
    145 mm of monthly rainfall
  • UV (maximum) index 3 (Moderate) in September in Donegal3
    3 (Moderate) UV index
  • 15°C sea temperature in September in Donegal15
    15°C sea temperature

More about Donegal

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The September weather guide for Ireland (Donegal) 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 Ireland

How warm is it in Donegal in September?

Daytime temperatures usually reach 15°C in Donegal in September, falling to 8°C at night.

How sunny is it in Donegal in September?

There are normally 3 hours of bright sunshine each day in Donegal in September - that's 27% of daylight hours.

How warm is the sea around Donegal in September?

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

Does it rain in Donegal in September?

There are usually 22 days with some rain in Donegal in September and the average monthly rainfall is 145mm.

Donegal September sunrise & sunset times

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

JanFebMarAprMayJunJulAugSepOctNovDec

Date Sunrise times Sunset times
Monday, 1st September 2025 05:40 19:24
Monday, 15th September 2025 06:05 18:49
Tuesday, 30th September 2025 06:33 18:10

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