Letterkenny weather in September 2025

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

  • 15°C maximum daytime temperature in September in Letterkenny15
    15°C max day temperature
  • 3 hours of sunshine per day
  • 22 days with some rainfall in September in Letterkenny22
    22 days with some rainfall
  • 8°C minimum night-time temperature in September in Letterkenny8
    8°C min night temperature
  • 13 hours of daylight per day in September in Letterkenny13
    13 hours of daylight per day
  • No heat & humidity in September in Letterkenny0
    No heat & humidity
  • 120 mm monthly rainfall in September in Letterkenny120
    120 mm of monthly rainfall
  • UV (maximum) index 3 (Moderate) in September in Letterkenny3
    3 (Moderate) UV index

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The September weather guide for Ireland (Letterkenny) 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 Letterkenny in September?

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

How sunny is it in Letterkenny in September?

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

Does it rain in Letterkenny in September?

There are usually 22 days with some rain in Letterkenny in September and the average monthly rainfall is 120mm.

Letterkenny September sunrise & sunset times

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

JanFebMarAprMayJunJulAugSepOctNovDec

Date Sunrise times Sunset times
Monday, 1st September 2025 05:38 19:23
Monday, 15th September 2025 06:04 18:47
Tuesday, 30th September 2025 06:32 18:09

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