The temperatures in Donegal in September are quite cold with temperatures between 9°C and 15°C, warm clothes are a must.
You can expect rain for roughly half of the month of September in Donegal. We’re expecting roughly 8 to 15 days of rain, so your rubber boots and umbrella are going to see plenty of use this month if you’re keen on staying dry.
Our weather forecast can give you a great sense of what weather to expect in Donegal in September 2025.
If you’re planning to visit Donegal in the near future, we highly recommend that you review the 14 day weather forecast for Donegal before you arrive.
Temperatures
15° / 9°
Rainy Days
10
Snowy Days
0
Dry Days
20
Rainfall
136
mm
Sun Hours
5.7
Hrs
