Belfast weather in August
Temperature, sea and sunshine in August: long-term averages from 30 years of weather data, not a forecast.
Holiday weather in August
Fair
Best time to visit: June – August
What is the weather like in Belfast in August?
In August, Belfast is mild: daytime highs average 17 °C, and nights cool down to about 13 °C. The sea averages 13.6 °C – swimming is only for the hardy. Expect around 5 hours of sunshine a day. It rains often – on about 15 days, adding up to 85 mm. All in all, August is a so-so month for a holiday in Belfast.
August compared
How the weather changes from July to September. Tap a month to open it.
| JulyJul | AugustAug | SeptemberSep | |
|---|---|---|---|
| Score | 57 | 57 | 50 |
| Day | 17° | 17° | 16° |
| Night | 13° | 13° | 12° |
| Sea | 13° | 14° | 14° |
| Sun | 5 h | 5 h | 4 h |
| Rain days | 15 | 15 | 14 |
More details for August
- Daylight
- 15 h 1 min05:58 – 20:59
- UV index
- 5 · moderateclear sky, noon (estimate)All months
- Muggy days
- 0 daysdew point 18 °C or moreAll months
- Wind
- 22 km/haverage daily peakAll months
- Cloud cover
- 73 %on averageAll months
- Hot days
- 0 days30 °C or more
- Snow days
- 0 days1 cm or more of fresh snow
- Time zone
- UTC+1Europe/London
How the score comes together
- Temperatureweight 50 %88 %
- Sunshineweight 20 %28 %
- Few rainy daysweight 30 %24 %
Each factor is rated from 0 to 100 % and weighted for the travel style “City break”.
What to pack in August
- Sunscreen
- A jumper for the evenings
- Rain jacket or umbrella
Belfast in August: quick answers
Is Belfast hot in August?
No. In August, Belfast is mild: daytime highs average 17 °C and nights drop to about 13 °C.
Can you swim in Belfast in August?
Only if you don't mind cold water: in August the sea averages just 13.6 °C. Comfortable swimming temperatures are not reached at any time of year.
Does it rain much in Belfast in August?
It rains often – on about 15 days, adding up to 85 mm.
Belfast month by month
The whole year in BelfastAll destinations: United KingdomWhere to go in AugustSea temperature in August
Climate averages 1996–2025, not a forecast. Data: Copernicus ERA5 / ERA5-Land via Open-Meteo.com (CC BY 4.0), NOAA OISST, WMO 1991–2020 (NOAA NCEI), GeoNames (CC BY 4.0). Sources & licences