The climate in Willemstad during September can be summarized as mild and reasonably dry.
September is in the fall / autumn in Willemstad and is typically the 4th warmest month of the year. Daytime maximum temperatures average around 19°C (65°F), whilst at night 10°C (51°F) is normal.
| Daytime temperature | 18.6°C 65.4°F |
|---|---|
| Nightly temperature | 10.3°C 50.5°F |
| Average temperature | 14.4°C 57.9°F |
| Daily sunshine | 5 hrs |
| Avg rainfall | 69 mm 2.7 ins |
| Rainy days | 15 days |
| Sea temperature | 17.7°C 63.9°F |
| Humidity | 82% |
| Windspeed | 15.5kph 10 mph |
On average September is the 6th wettest month of the year in Willemstad with around 69mm 2.7 inches of rain making it a reasonably dry time to visit. This rainfall is typically spread over 15 days, although this may vary considerably.
On the flip side this corresponds to an average of 5 hours of sunshine per day.
The data used in these monthly averages covers a period of over 100 years right up until last year. As such they are a valid prediction of what to expect for the weather in Willemstad in September 2025.
Best places to visit in September
| Hottest month: | July | 21.1°C 70°F |
|---|---|---|
| Driest month: | February | 46mm 1.8ins |
| Sunniest month: | May | 7.3hrs |
| Coldest month: | January | 5.2°C 41.4°F |
| Wettest month: | November | 79mm 3.1ins |