Month by month
| Month | Afternoon | Sea | Rain | Verdict |
|---|---|---|---|---|
| January | 7.3 °C | 9.5 °C | 14 days | Unfavourable season |
| February | 8 °C | 8.6 °C | 14 days | Unfavourable season |
| March | 9.3 °C | 8.2 °C | 16 days | Unfavourable season |
| April | 11 °C | 8.6 °C | 13 days | Unfavourable season |
| May | 14.6 °C | 9.6 °C | 14 days | Possible, with trade-offs |
| June | 17.1 °C | 11.1 °C | 14 days | Possible, with trade-offs |
| July | 18.2 °C | 12.6 °C | 18 days | Possible, with trade-offs |
| August | 18 °C | 13.7 °C | 18 days | Possible, with trade-offs |
| September | 16.1 °C | 14.2 °C | 14 days | Possible, with trade-offs |
| October | 13.2 °C | 13.8 °C | 14 days | Possible, with trade-offs |
| November | 9.9 °C | 12.7 °C | 14 days | Unfavourable season |
| December | 8.5 °C | 11 °C | 15 days | Unfavourable season |
Before you go
Three things to check once you have picked your dates.
Entry
Entry rules depend on your nationality and change often. Check them before booking.
Safety
No advisory published for this destination.
Health
Recommended vaccinations, water quality, mosquitoes: advice depends on the country and the season. Some vaccines need time before departure.
Beau Fixe is not a safety or health authority. These notes summarise public advisories and link to their source; only the competent authorities are authoritative. Alert levels: Foreign, Commonwealth & Development Office (gov.uk), Open Government Licence v3.0.
FAQ
Can you swim in Belfast in September?
The sea averages 14.2°C in September — too cold for most swimmers.
How hot is Belfast in September?
Expect 16.1°C in the afternoon and 10.5°C at night, averaged over the last 10 years.
Does it rain a lot in Belfast in September?
Around 14 days with rain (≥ 1 mm) in the month — 47% of days.