The highest day temperature in September 2026 was 79°F. The lowest night temperature was 52°F. The average values for day and night temperatures during September were 68.9°F и 60.0°F respectivly.

The average sea surface temperature in September 2026 for Rotterdam was 68.3°F. The maximum and minimum values were 66.0°F and 70.2°F respectively.

You can expect various weather conditions during September. Be ready for sunny, cloudy or even gloomy days.

Precipitation total in September for Rotterdam is 1.6 in.

The average wind speed in September is 9.0 mph. It makes September the most windless month of the year for Rotterdam.

We are using day length and cloud cover information for each day of the month to calculate averages for this chart. Average sunny hours for Rotterdam in September is 6.6 hours.