Climate averages 1991–2020
Belfast weather
in August.
A mild, moderately wet month: the 2nd warmest and the joint 8th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
August is a mild month in Belfast: daytime highs average 17.3°C and nights cool to about 12.6°C. By daytime temperature it is the 2nd warmest of the 12 months.
Expect about 81 mm of rain on roughly 14 days, which makes August a moderately wet month (the joint 8th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 14 h 56 min on an average August day.
The nearest other city in this atlas is Lisburn (11 km away). In August its highs average 17.4°C, about as warm as Belfast, with 81 mm of rain.
Among the 143 cities listed in the United Kingdom, Belfast ranks joint 137th of 143 for the warmest August highs and joint 115th of 143 for the driest August (rainfall, lowest first). The mean August high of those 143 cities is 19.7°C; Belfast is 2.4°C cooler than that mean.
From August to September, average highs fall by 1.7°C to 15.7°C, and monthly rainfall falls from 81 mm to 70 mm.
The annual picture
August in context
Monthly rainfall
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
Belfast climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 7.5°C3.9°C | 3.9°C | 77 | 14.2 | 7.98 h |
| February | 7.7°C3.8°C | 3.8°C | 63 | 12.2 | 9.710 h |
| March | 9.1°C4.4°C | 4.4°C | 62 | 13.4 | 11.812 h |
| April | 10.9°C5.9°C | 5.9°C | 65 | 13.0 | 14.014 h |
| May | 13.6°C8.2°C | 8.2°C | 70 | 14.1 | 16.016 h |
| June | 15.9°C10.9°C | 10.9°C | 75 | 13.2 | 17.217 h |
| July | 17.4°C12.5°C | 12.5°C | 81 | 14.6 | 16.717 h |
| August, selected | 17.3°C12.6°C | 12.6°C | 81 | 14.2 | 14.915 h |
| September | 15.7°C11.3°C | 11.3°C | 70 | 12.5 | 12.813 h |
| October | 12.8°C9.0°C | 9.0°C | 86 | 13.5 | 10.611 h |
| November | 9.8°C6.4°C | 6.4°C | 85 | 14.0 | 8.59 h |
| December | 7.9°C4.4°C | 4.4°C | 82 | 13.5 | 7.47 h |
Rainfall is the average of the 30 separate monthly totals. A rain day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
August in nearby cities
- Lisburn in AugustUnited Kingdom · 11 kmHigh 17.4°C · Low 12.1°C · 81 mm rain
- Derry in AugustUnited Kingdom · 99 kmHigh 17.1°C · Low 11.9°C · 94 mm rain
- Douglas in AugustIsle of Man · 106 kmHigh 16.0°C · Low 14.0°C · 78 mm rain
- Dublin in AugustIreland · 142 kmHigh 18.6°C · Low 12.8°C · 78 mm rain
- Tallaght in AugustIreland · 149 kmHigh 18.2°C · Low 12.3°C · 78 mm rain
- Paisley in AugustUnited Kingdom · 167 kmHigh 17.2°C · Low 11.1°C · 105 mm rain
- East Kilbride in AugustUnited Kingdom · 171 kmHigh 16.6°C · Low 10.2°C · 101 mm rain
- Glasgow in AugustUnited Kingdom · 176 kmHigh 17.2°C · Low 10.9°C · 101 mm rain
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for Belfast) is explained once on the Belfast year overview and on the Sources, method and limits page.
Lisburn lies in the same rainfall cell, so its rainfall figures are identical to these; temperatures differ because they come from smaller 0.1° cells.