The temperatures in Londonderry in September are quite cold with temperatures between 9°C and 17°C, warm clothes are a must.
You can expect about 3 to 8 days of rain in Londonderry during the month of September. It’s a good idea to bring along your umbrella so that you don’t get caught in poor weather.
Our weather forecast can give you a great sense of what weather to expect in Londonderry in September 2025.
If you’re planning to visit Londonderry in the near future, we highly recommend that you review the 14 day weather forecast for Londonderry before you arrive.
Temperatures
17° / 9°
Rainy Days
3
Snowy Days
0
Dry Days
27
Rainfall
35
mm
Sun Hours
9.4
Hrs
