Climate averages 1991–2020
Rotterdam weather
in September.
A mild, moderately wet month: the 4th warmest and the 9th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
September is a mild month in Rotterdam: daytime highs average 18.5°C and nights cool to about 12.0°C. By daytime temperature it is the 4th warmest of the 12 months.
Expect about 69 mm of rain on roughly 12 days, which makes September a moderately wet month (the 9th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 12 h 43 min on an average September day.
The nearest other city in this atlas is Schiedam (6 km away). In September its highs average 18.5°C, about as warm as Rotterdam, with 69 mm of rain.
Among the 44 cities listed in the Netherlands, Rotterdam ranks joint 18th of 44 for the warmest September highs and joint 27th of 44 for the driest September (rainfall, lowest first). The mean September high of those 44 cities is 18.4°C; Rotterdam is 0.1°C warmer than that mean.
From September to October, average highs fall by 4.1°C to 14.3°C, and monthly rainfall falls from 69 mm to 68 mm.
The annual picture
September in context
Monthly rainfall
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
Rotterdam climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 5.9°C1.6°C | 1.6°C | 62 | 12.2 | 8.38 h |
| February | 6.8°C1.5°C | 1.5°C | 52 | 10.9 | 9.910 h |
| March | 9.8°C3.2°C | 3.2°C | 53 | 11.3 | 11.812 h |
| April | 13.6°C5.6°C | 5.6°C | 48 | 10.9 | 13.914 h |
| May | 17.0°C9.2°C | 9.2°C | 61 | 11.5 | 15.616 h |
| June | 19.6°C12.1°C | 12.1°C | 64 | 11.0 | 16.617 h |
| July | 21.7°C14.4°C | 14.4°C | 79 | 13.4 | 16.216 h |
| August | 21.6°C14.4°C | 14.4°C | 79 | 13.0 | 14.715 h |
| September, selected | 18.5°C12.0°C | 12.0°C | 69 | 12.1 | 12.713 h |
| October | 14.3°C8.7°C | 8.7°C | 68 | 12.6 | 10.711 h |
| November | 9.7°C5.2°C | 5.2°C | 66 | 13.5 | 8.99 h |
| December | 6.4°C2.4°C | 2.4°C | 71 | 13.5 | 7.98 h |
Rainfall is the average of the 30 separate monthly totals. A rain day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
September in nearby cities
- Schiedam in SeptemberThe Netherlands · 6 kmHigh 18.5°C · Low 12.3°C · 69 mm rain
- Vlaardingen in SeptemberThe Netherlands · 9 kmHigh 18.4°C · Low 12.5°C · 74 mm rain
- Delft in SeptemberThe Netherlands · 13 kmHigh 18.3°C · Low 12.5°C · 74 mm rain
- Spijkenisse in SeptemberThe Netherlands · 13 kmHigh 18.5°C · Low 12.2°C · 64 mm rain
- Zoetermeer in SeptemberThe Netherlands · 15 kmHigh 18.3°C · Low 12.5°C · 69 mm rain
- Dordrecht in SeptemberThe Netherlands · 18 kmHigh 18.6°C · Low 11.8°C · 61 mm rain
- Gouda in SeptemberThe Netherlands · 19 kmHigh 18.4°C · Low 12.0°C · 67 mm rain
- The Hague in SeptemberThe Netherlands · 21 kmHigh 18.1°C · Low 13.0°C · 74 mm rain
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for Rotterdam) is explained once on the Rotterdam year overview and on the Sources, method and limits page.
Zoetermeer and Schiedam lie in the same rainfall cell, so their rainfall figures are identical to these; temperatures differ because they come from smaller 0.1° cells.