Northern Ireland weather in September 2025

Q: How warm is it in Northern Ireland in September?

Daytime temperatures usually reach 16°C in Belfast, Northern Ireland in September, falling to 9°C at night.

Q: How sunny is it in Northern Ireland in September?

There are normally 4 hours of bright sunshine each day in Belfast, Northern Ireland in September - that's 30% of daylight hours.

Q: How warm is the sea around Northern Ireland in September?

The average sea temperature around Belfast, Northern Ireland in September is 14°C.

Q: Does it rain in Northern Ireland in September?

There are usually 17 days with some rain in Belfast, Northern Ireland in September and the average monthly rainfall is 94mm.

Expect daytime maximum temperatures of 16°C in Northern Ireland, UK in September based on long-term weather averages. There are 4 hours of sunshine per day on average with 17 days with some rainfall and typically 94 mm of rainfall in the month.

16
16°C max day temperature
4
4 hours of sunshine per day
17
17 days with some rainfall
9
9°C min night temperature
13
13 hours of daylight per day
0
No heat & humidity
94
94 mm of monthly rainfall
3
3 (Moderate) UV index
14
14°C sea temperature

More about Northern Ireland

Northern Ireland by month

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Recommended for Northern Ireland

Spabreaks.com: Latest offers on UK spa days

Sale

Check out latest special offers on spa days in the UK
Filter offers by price, destination, package & facilities
Book spa days in popular cities & country locations

Go to Spabreaks.com deal >>

View all Spabreaks.com offers

The September weather guide for Northern Ireland (Belfast) 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.

Top Northern Ireland destinations

Below are average maximum temperatures at popular countries, regions and places in Northern Ireland in September. Select a holiday destination to see more weather parameters.

16
Belfast
15
Londonderry

All Northern Ireland destinations

Metric (°C / mm) | Imperial (°F / inches)

More about the UK

How warm is it in Northern Ireland in September?

Daytime temperatures usually reach 16°C in Belfast, Northern Ireland in September, falling to 9°C at night.

How sunny is it in Northern Ireland in September?

There are normally 4 hours of bright sunshine each day in Belfast, Northern Ireland in September - that's 30% of daylight hours.

How warm is the sea around Northern Ireland in September?

The average sea temperature around Belfast, Northern Ireland in September is 14°C.

Does it rain in Northern Ireland in September?

There are usually 17 days with some rain in Belfast, Northern Ireland in September and the average monthly rainfall is 94mm.

Northern Ireland September sunrise & sunset times

Browse the sunrise and sunset times for Northern Ireland in September 2025. Select a month to view Northern Ireland sunrise and sunset times for the next 12 months. The Northern Ireland sunrise and sunset times shown below are for Belfast.

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec