Month by month
| Month | Afternoon | Sea | Rain | Verdict |
|---|---|---|---|---|
| January | 4.6 °C | 4.4 °C | 14 days | Unfavourable season |
| February | 5.6 °C | 3.6 °C | 11 days | Unfavourable season |
| March | 7.6 °C | 4.4 °C | 12 days | Unfavourable season |
| April | 11.1 °C | 7.1 °C | 11 days | Unfavourable season |
| May | 15.8 °C | 11.5 °C | 11 days | Possible, with trade-offs |
| June | 19.8 °C | 16.1 °C | 11 days | Pleasant — a good time to go |
| July | 20.6 °C | 18 °C | 14 days | Possible, with trade-offs |
| August | 21.1 °C | 18.8 °C | 13 days | Pleasant — a good time to go |
| September | 18 °C | 17.1 °C | 11 days | Possible, with trade-offs |
| October | 13.4 °C | 13.4 °C | 14 days | Possible, with trade-offs |
| November | 8.6 °C | 9.9 °C | 14 days | Unfavourable season |
| December | 6.1 °C | 6.4 °C | 14 days | Unfavourable season |
Before you go
Three things to check once you have picked your dates.
Entry
Denmark is in the European Union. Entry rules depend on your nationality — check before booking.
Safety
No specific restrictions
Usual precautions apply.
Official advice updated 11 August 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 Sønderborg in August?
The sea averages 18.8°C in August — too cold for most swimmers.
How hot is Sønderborg in August?
Expect 21.1°C in the afternoon and 14.6°C at night, averaged over the last 10 years.
Does it rain a lot in Sønderborg in August?
Around 13 days with rain (≥ 1 mm) in the month — 42% of days.