September weather forecastHarmondsworth, United Kingdom
September
Weather in September
The first month of the autumn, September, is also an enjoyable month in Harmondsworth, United Kingdom, with an average temperature fluctuating between 11°C (51.8°F) and 18.8°C (65.8°F).Temperature
Harmondsworth's weather, upon September's arrival, documents an average high-temperature of a refreshing 18.8°C (65.8°F), nearly identical to the prior month. In Harmondsworth, an average low-temperature of 11°C (51.8°F) is recorded during September nights.Humidity
In Harmondsworth, the average relative humidity in September is 78%.Rainfall
In Harmondsworth, during September, the rain falls for 7 days and regularly aggregates up to 10mm (0.39") of precipitation. Throughout the year, in Harmondsworth, there are 109 rainfall days, and 156mm (6.14") of precipitation is accumulated.Snowfall
In Harmondsworth, snow does not fall in April through November.Daylight
In Harmondsworth, the average length of the day in September is 12h and 38min.On the first day of the month, sunrise is at 6:15 am and sunset at 7:47 pm. On the last day of September, sunrise is at 7:01 am and sunset at 6:41 pm BST.
Sunshine
The average sunshine in September is 7.1h.UV index
The average daily maximum UV index in September in Harmondsworth is 4. A UV Index of 3 to 5 symbolizes a medium vulnerability from unsafe exposure to UV radiation for average individuals.Note: A typical high UV index of 4 in September suggests the following recommendations:
Proceed with care. Light skin individuals may be exposed to burns in fewer than 30 minutes. The Sun is at its harshest during midday; protect yourself by staying in shaded areas and minimizing exposure. Sunglasses that guard against UVA and UVB rays are pivotal in minimizing sun-induced ocular damage.
Published by: Weather Atlas | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Harmondsworth, United Kingdom
- Average high temperature in September: 18.8°C
The warmest month (with the highest average high temperature) is July (22°C).
The month with the lowest average high temperature is January (6.8°C).
- Average low temperature in September: 11°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 (1.9°C).
Average pressure in September
Harmondsworth, United Kingdom
- Average pressure in September: 1016.9mbar
The month with the highest atmospheric pressure is September (1016.9mbar).
The month with the lowest atmospheric pressure is November (1010.5mbar).
Average wind speed in September
Harmondsworth, United Kingdom
- Average wind speed in September: 12.7km/h
The windiest month (with the highest average wind speed) is February (17.5km/h).
The calmest months (with the lowest average wind speed) are July and September (12.7km/h).
Average humidity in September
Harmondsworth, United Kingdom
- Average humidity in September: 78%
The month with the highest relative humidity is December (89%).
The months with the lowest relative humidity are July and August (74%).
Average rainfall in September
Harmondsworth, United Kingdom
- Average rainfall in September: 10mm
The wettest month (with the highest rainfall) is June (21mm).
The driest months (with the least rainfall) are January, March, April and May (9mm).
Average rainfall days in September
Harmondsworth, United Kingdom
- Average rainfall days in September: 7 days
The month with the highest number of rainy days is June (12.3 days).
The month with the least rainy days is January (6.8 days).
Average snowfall in September
Harmondsworth, United Kingdom
- Average snowfall in September: 0mm
The months with the highest snowfall are January and February (6mm).
The months with the least snowfall are April, May, June, July, August, September, October and November (0mm).
Average snowfall days in September
Harmondsworth, United Kingdom
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is February (2 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
Harmondsworth, United Kingdom
- Average daylight in September: 12h and 36min
The month with the longest days is June (Average daylight: 16h and 36min).
The month with the shortest days is December (Average daylight: 7h and 54min).
- Average sunshine in September: 7h and 6min
The month with the most sunshine is July (Average sunshine: 7h and 54min).
The month with the least sunshine is February (Average sunshine: 3h and 42min).
Average sunshine days in September
Harmondsworth, United Kingdom
- Average sunshine days in September: 19.8 days
The month with the most sunshine days is October (20.2 days).
The months with the least sunshine days are June and July (14.2 days).
Average UV index in September
Harmondsworth, United Kingdom
- 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
Harmondsworth, United Kingdom
- Average cloud cover in September: 50
The month with the most cloud cover is February (Cloud cover 61).
The month with the least cloud cover is April (Cloud cover 49).
Average visibility in September
Harmondsworth, United Kingdom
- Average visibility in September: 9km
The months with the highest visibility are January, February, March, April, May, June, July, August, September, October and December (9km).
The month with the lowest visibility is November (8km).
