Month by month
| Month | Afternoon | Sea | Rain | Verdict |
|---|---|---|---|---|
| January | 6.8 °C | 7.1 °C | 15 days | Unfavourable season |
| February | 8.2 °C | 6.2 °C | 12 days | Unfavourable season |
| March | 10.5 °C | 6.9 °C | 14 days | Unfavourable season |
| April | 13.5 °C | 9 °C | 11 days | Possible, with trade-offs |
| May | 17.6 °C | 12.2 °C | 12 days | Possible, with trade-offs |
| June | 21.2 °C | 15.9 °C | 11 days | Pleasant — a good time to go |
| July | 22.1 °C | 18.3 °C | 14 days | Possible, with trade-offs |
| August | 22.7 °C | 19.6 °C | 13 days | Pleasant — a good time to go |
| September | 19.7 °C | 18.4 °C | 11 days | Pleasant — a good time to go |
| October | 15.4 °C | 15.4 °C | 14 days | Possible, with trade-offs |
| November | 10.5 °C | 12 °C | 15 days | Unfavourable season |
| December | 8.1 °C | 8.8 °C | 15 days | Unfavourable season |
Before you go
Three things to check once you have picked your dates.
Entry
Netherlands 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 Rotterdam in September?
The sea averages 18.4°C in September — too cold for most swimmers.
How hot is Rotterdam in September?
Expect 19.7°C in the afternoon and 12.4°C at night, averaged over the last 10 years.
Does it rain a lot in Rotterdam in September?
Around 11 days with rain (≥ 1 mm) in the month — 38% of days.