Month by month
| Month | Afternoon | Sea | Rain | Verdict |
|---|---|---|---|---|
| January | 3.3 °C | 4.9 °C | 15 days | Unfavourable season |
| February | 4.8 °C | 4 °C | 12 days | Unfavourable season |
| March | 7.6 °C | 4.2 °C | 10 days | Unfavourable season |
| April | 11.4 °C | 6.1 °C | 9 days | Unfavourable season |
| May | 16.4 °C | 9.9 °C | 11 days | Possible, with trade-offs |
| June | 20.7 °C | 15 °C | 10 days | Pleasant — a good time to go |
| July | 21.3 °C | 18.2 °C | 15 days | Possible, with trade-offs |
| August | 22.6 °C | 19.2 °C | 13 days | Pleasant — a good time to go |
| September | 19.1 °C | 17.3 °C | 12 days | Pleasant — a good time to go |
| October | 13.5 °C | 13.4 °C | 15 days | Possible, with trade-offs |
| November | 8 °C | 10.1 °C | 13 days | Unfavourable season |
| December | 4.8 °C | 6.9 °C | 14 days | Unfavourable season |
Before you go
Three things to check once you have picked your dates.
Entry
Poland 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 Koszalin in September?
The sea averages 17.3°C in September — too cold for most swimmers.
How hot is Koszalin in September?
Expect 19.1°C in the afternoon and 12.4°C at night, averaged over the last 10 years.
Does it rain a lot in Koszalin in September?
Around 12 days with rain (≥ 1 mm) in the month — 41% of days.