Climate averages 1991–2020
Belfast weather
in May.
A cool, moderately wet month: the 5th warmest and the joint 4th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
May is a cool month in Belfast: daytime highs average 13.6°C and nights cool to about 8.2°C. By daytime temperature it is the 5th warmest of the 12 months.
Expect about 70 mm of rain on roughly 14 days, which makes May a moderately wet month (the joint 4th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 16 h 02 min on an average May day.
The nearest other city in this atlas is Lisburn (11 km away). In May its highs average 13.8°C, about as warm as Belfast, with 70 mm of rain.
Among the 143 cities listed in the United Kingdom, Belfast ranks joint 134th of 143 for the warmest May highs and joint 129th of 143 for the driest May (rainfall, lowest first). The mean May high of those 143 cities is 15.2°C; Belfast is 1.6°C cooler than that mean.
From May to June, average highs rise by 2.4°C to 15.9°C, and monthly rainfall rises from 70 mm to 75 mm.
The annual picture
May 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, selected | 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 | 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
May in nearby cities
- Lisburn in MayUnited Kingdom · 11 kmHigh 13.8°C · Low 7.7°C · 70 mm rain
- Derry in MayUnited Kingdom · 99 kmHigh 13.8°C · Low 7.6°C · 78 mm rain
- Douglas in MayIsle of Man · 106 kmHigh 11.7°C · Low 9.3°C · 56 mm rain
- Dublin in MayIreland · 142 kmHigh 14.7°C · Low 8.3°C · 66 mm rain
- Tallaght in MayIreland · 149 kmHigh 14.4°C · Low 7.8°C · 66 mm rain
- Paisley in MayUnited Kingdom · 167 kmHigh 13.8°C · Low 6.6°C · 78 mm rain
- East Kilbride in MayUnited Kingdom · 171 kmHigh 13.2°C · Low 5.7°C · 79 mm rain
- Glasgow in MayUnited Kingdom · 176 kmHigh 13.7°C · Low 6.3°C · 79 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.