Belfast weather in August 2025

Q: How hot is it in Belfast in August?

Daytime temperatures usually reach 18°C in Belfast in August, falling to 11°C at night.

Q: How sunny is it in Belfast in August?

There are normally 5 hours of bright sunshine each day in Belfast in August - that's 32% of daylight hours.

Q: How warm is the sea around Belfast in August?

The average sea temperature around Belfast in August is 13°C.

Q: Does it rain in Belfast in August?

There are usually 17 days with some rain in Belfast in August and the average monthly rainfall is 89mm.

Expect 18°C daytime maximum temperatures in the shade with on average 5 hours of sunshine per day in Belfast in August. Check more long-term weather averages for Belfast in August before you book your next holiday to Northern Ireland in 2025/2026.

18
18°C max day temperature
5
5 hours of sunshine per day
17
17 days with some rainfall
11
11°C min night temperature
15
15 hours of daylight per day
0
No heat & humidity
89
89 mm of monthly rainfall
5
5 (Moderate) UV index
13
13°C sea temperature

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The August 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.

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