September is a two-sided month. The first two weeks can still be fully summery, with temperatures above 22°C and enough sun to sit outside. But as the month progresses, the character of the weather shifts quickly. The beginning of the end of shorts season.
How warm is September?
Average daytime temperatures in September drop from around 21°C at the start to 16–17°C at the end. That still sounds manageable, but the autumn wind — which picks up early in September — pushes the feels-like temperature down quickly.
| Period | Avg. daytime temp. | Feels-like temp. with wind (25 km/h) |
|---|---|---|
| Early September | 20–22°C | 17–19°C |
| Mid September | 17–19°C | 13–16°C |
| Late September | 15–17°C | 11–13°C |
Early September: summer feeling persists
In the first week or two of September, shorts are perfectly fine. Temperatures are still summery, evenings cool slightly but remain pleasant. This is the extended summer to make the most of.
Can you wear shorts today?
Check it now for your location — free, no account needed.
Mid September: the tipping point
Around mid September the weather shifts. More cloud cover, more rain and the first cold nights. Daytime temperatures can still reach 18–20°C on sunny days, but overcast days already feel distinctly autumnal. Shorts still work on the good days, but the chance of it being warm enough drops fast.
Late September: put the shorts away
By late September, the average feels-like temperature in the Netherlands is too low for most people in shorts. With wind and cloud cover you quickly reach 10–12°C — at that point long trousers are not a luxury but a necessity. The sun is also lower in the sky, so there's less radiant warmth to compensate for the cold.
The role of acclimatisation in autumn
Just as in spring, adaptation plays a role — but in reverse. After a warm summer your body is set to warmth. 17°C in September therefore feels colder than the same temperature in May. You reach for a jacket sooner than strictly necessary, and that's fine.
Conclusion
In September you can wear shorts until roughly the middle of the month, in fine sunny weather. By late September it's definitively too cold for most people. Check the feels-like temperature and wind speed each day — September is too variable to rely on without a current forecast.