September weather forecastHeerlen, Netherlands
September
Weather in September
September signals the beginning of autumn in Heerlen. The weather turns relatively cooler, signaling the retreat of summer. Gold-hued leaves, cooler temperatures, and crisp autumn air become synonymous with September. Noteworthy is that wind speed manifests a minor increase compared to August, moving up to 11.4km/h (7.1mph); this factor amplifies the autumnal feel in the city. As the month proceeds, the frequency and volume of rainfall start to augment, leading to slightly wetter conditions.Temperature
September brings a slight decrease in temperature, down from a pleasant 22.6°C (72.7°F) in August to a comfortable 18.7°C (65.7°F). September nights in Heerlen are marked by an average temperature drop to a cool 10.5°C (50.9°F).Humidity
The average relative humidity in September is 80%.Rainfall
In Heerlen, in September, during 12.2 rainfall days, 28mm (1.1") of precipitation is typically accumulated. In Heerlen, during the entire year, the rain falls for 182.5 days and collects up to 482mm (18.98") of precipitation.Snowfall
April through October are months without snowfall in Heerlen.Daylight
In Heerlen, the average length of the day in September is 12h and 38min.On the first day of September in Heerlen, sunrise is at 06:50 and sunset at 20:21. On the last day of the month, sunrise is at 07:35 and sunset at 19:16 CEST.
Sunshine
In Heerlen, the average sunshine in September is 7.9h.UV index
In Heerlen, the average daily maximum UV index in September is 4. A UV Index of 3 to 5 symbolizes a medium vulnerability from unsafe exposure to UV radiation for the average person.Note: An average maximum UV index of 4 in September leads to these recommendations:
Be mindful. Individuals with a lighter skin tone may suffer burns in less than 30 minutes. Solar radiation is at its peak intensity during midday, so it's advisable to stay indoors or in the shade. To cut down UV radiation exposure by about half, sport a wide-brim hat.
Published by: Weather Atlas | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Heerlen, Netherlands
- Average high temperature in September: 18.7°C
The warmest months (with the highest average high temperature) are July and August (22.6°C).
The month with the lowest average high temperature is January (4.3°C).
- Average low temperature in September: 10.5°C
The month with the highest average low temperature is August (13.7°C).
The coldest month (with the lowest average low temperature) is January (0.4°C).
Average pressure in September
Heerlen, Netherlands
- Average pressure in September: 1017.6mbar
The month with the highest atmospheric pressure is September (1017.6mbar).
The month with the lowest atmospheric pressure is November (1013.1mbar).
Average wind speed in September
Heerlen, Netherlands
- Average wind speed in September: 11.4km/h
The windiest month (with the highest average wind speed) is December (17.6km/h).
The calmest month (with the lowest average wind speed) is August (11.1km/h).
Average humidity in September
Heerlen, Netherlands
- Average humidity in September: 80%
The months with the highest relative humidity are January and December (87%).
The month with the lowest relative humidity is April (75%).
Average rainfall in September
Heerlen, Netherlands
- Average rainfall in September: 28mm
The wettest month (with the highest rainfall) is December (51mm).
The driest month (with the least rainfall) is April (22mm).
Average rainfall days in September
Heerlen, Netherlands
- Average rainfall days in September: 12.2 days
The months with the highest number of rainy days are May and July (18 days).
The month with the least rainy days is September (12.2 days).
Average snowfall in September
Heerlen, Netherlands
- Average snowfall in September: 0mm
The month with the highest snowfall is January (48mm).
The months with the least snowfall are April, May, June, July, August, September and October (0mm).
Average snowfall days in September
Heerlen, Netherlands
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (5.9 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).
Average daylight in September /
Average sunshine in September
Heerlen, Netherlands
- Average daylight in September: 12h and 36min
The month with the longest days is June (Average daylight: 16h and 24min).
The month with the shortest days is December (Average daylight: 8h and 0min).
- Average sunshine in September: 7h and 54min
The month with the most sunshine is August (Average sunshine: 9h and 12min).
The month with the least sunshine is December (Average sunshine: 3h and 42min).
Average sunshine days in September
Heerlen, Netherlands
- Average sunshine days in September: 15.5 days
The months with the most sunshine days are September and October (15.5 days).
The month with the least sunshine days is June (9.8 days).
Average UV index in September
Heerlen, Netherlands
- Average UV index in September: 4
The months with the highest UV index are June and July (UV index 5).
The months with the lowest UV index are January, February, November and December (UV index 2).
Average cloud cover in September
Heerlen, Netherlands
- Average cloud cover in September: 42
The month with the most cloud cover is December (Cloud cover 63).
The month with the least cloud cover is August (Cloud cover 40).
Average visibility in September
Heerlen, Netherlands
- Average visibility in September: 9km
The months with the highest visibility are February, March, April, May, June, July, August, September, October and November (9km).
The months with the lowest visibility are January and December (8km).
