Month by month
| Month | Afternoon | Sea | Rain | Verdict |
|---|---|---|---|---|
| January | 8.4 °C | 9.3 °C | 13 days | Unfavourable season |
| February | 9.1 °C | 8.6 °C | 13 days | Unfavourable season |
| March | 10 °C | 8.3 °C | 15 days | Unfavourable season |
| April | 11.5 °C | 9.2 °C | 13 days | Unfavourable season |
| May | 14.8 °C | 11.2 °C | 14 days | Possible, with trade-offs |
| June | 17.5 °C | 13.7 °C | 13 days | Possible, with trade-offs |
| July | 19 °C | 15.2 °C | 15 days | Possible, with trade-offs |
| August | 18.8 °C | 15.4 °C | 14 days | Possible, with trade-offs |
| September | 16.9 °C | 14.8 °C | 13 days | Possible, with trade-offs |
| October | 14.1 °C | 13.6 °C | 15 days | Possible, with trade-offs |
| November | 10.7 °C | 12.3 °C | 14 days | Unfavourable season |
| December | 9.5 °C | 10.6 °C | 16 days | Unfavourable season |
Before you go
Three things to check once you have picked your dates.
Entry
Ireland is in the European Union. Entry rules depend on your nationality — check before booking.
Safety
No specific restrictions
Usual precautions apply.
Official advice updated 4 September 2026
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 Dún Laoghaire in June?
The sea averages 13.7°C in June — too cold for most swimmers.
How hot is Dún Laoghaire in June?
Expect 17.5°C in the afternoon and 11.6°C at night, averaged over the last 10 years.
Does it rain a lot in Dún Laoghaire in June?
Around 13 days with rain (≥ 1 mm) in the month — 45% of days.