Portstewart weather in September 2025

Q: How warm is it in Portstewart in September?

Daytime temperatures usually reach 15°C in Portstewart in September, falling to 9°C at night.

Q: How sunny is it in Portstewart in September?

There are normally 3 hours of bright sunshine each day in Portstewart in September - that's 26% of daylight hours.

Q: How warm is the sea around Portstewart in September?

The average sea temperature around Portstewart in September is 14°C.

Q: Does it rain in Portstewart in September?

There are usually 20 days with some rain in Portstewart in September and the average monthly rainfall is 107mm.

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

15
15°C max day temperature
3
3 hours of sunshine per day
20
20 days with some rainfall
9
9°C min night temperature
13
13 hours of daylight per day
0
No heat & humidity
107
107 mm of monthly rainfall
3
3 (Moderate) UV index
14
14°C sea temperature

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The September weather guide for Northern Ireland (Portstewart) 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)

More about the UK

How warm is it in Portstewart in September?

Daytime temperatures usually reach 15°C in Portstewart in September, falling to 9°C at night.

How sunny is it in Portstewart in September?

There are normally 3 hours of bright sunshine each day in Portstewart in September - that's 26% of daylight hours.

How warm is the sea around Portstewart in September?

The average sea temperature around Portstewart in September is 14°C.

Does it rain in Portstewart in September?

There are usually 20 days with some rain in Portstewart in September and the average monthly rainfall is 107mm.

Portstewart September sunrise & sunset times

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

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