September weather forecast
London, United Kingdom

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The large Thames river overlooking the Westminster Palace and the Big Ben clock tower in London, United Kingdom
The large Thames river overlooking the Westminster Palace and the Big Ben clock tower in London, United Kingdom

Weather in September

In September, London gradually starts to wave goodbye to summer. The weather, while remaining reasonably fair, shows noticeable changes from August. With the approaching October, further drops in temperature can be expected. However, the crisp air and fewer tourists make September an agreeable month to explore London. With the lowest average cloud coverage of 49% throughout the year, September promises relatively clear skies.

Temperature

The average high-temperature in September, at a comfortable 19°C (66.2°F), reveals a modest deviation from August's 21.9°C (71.4°F). An average low-temperature of 11.3°C (52.3°F) is observed during September nights in London, United Kingdom.

Humidity

In London, the average relative humidity in September is 76%.

Rainfall

In September, the rain falls for 9.8 days. Throughout September, 26mm (1.02") of precipitation is accumulated. In London, during the entire year, the rain falls for 151.7 days and collects up to 370mm (14.57") of precipitation.

Snowfall

In London, United Kingdom, snow does not fall in May through October.

Daylight

In September, the average length of the day is 12h and 38min.
On the first day of the month, sunrise is at 6:14 am and sunset at 7:46 pm. On the last day of September, in London, sunrise is at 7:00 am and sunset at 6:40 pm BST.

Sunshine

In London, the average sunshine in September is 7.1h.

UV index

In London, United Kingdom, the average daily maximum UV index in September is 4. A UV Index of 3 to 5 symbolizes a medium vulnerability from exposure to the Sun's UV rays for the ordinary person.
Note: In September, the maximum UV index of 4 transforms into these recommendations:
Guard yourself - Precautionary measures against sun damage are advocated. It's crucial to reduce time in the direct Sun around mid-day due to the intense solar radiation. During bright days, sunglasses that offer UVA and UVB defense are recommended.
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Frequently asked questions

What is the usual temperature for London in September?

The average high-temperature and low-temperature in London, United Kingdom, during September are 19°C (66.2°F) and 11.3°C (52.3°F) respectively.

What is the average humidity in September in London?

The average relative humidity in September is 76%.

How many days does it rain in September in London?

In London, in September, it is raining for 9.8 days, with typically 26mm (1.02") of accumulated precipitation.

When it does not snow in London?

In London, United Kingdom, snow does not fall in May through October.

How many hours of daylight does London have in September?

In London, United Kingdom, the average day length in September is 12h and 38min.

When are sunrise and sunset in September in London?

On the first day of September in London, sunrise is at 6:14 am and sunset at 7:46 pm. On the last day of the month, sunrise is at 7:00 am and sunset at 6:40 pm BST.

How long on average sun shines in September in London?

The average sunshine duration in September in London, United Kingdom, is 7.1h.

What is the UV index intensity in September in London?

The average daily maximum UV index in September in London, United Kingdom, is 4. A UV Index value of 3 to 5 symbolizes a moderate vulnerability from exposure to the Sun's UV radiation.
Average humidity
Average rainfall days
Average snowfall
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
London, United Kingdom

Average temperature in September - London, United Kingdom
  • Average high temperature in September: 19°C

The warmest month (with the highest average high temperature) is July (22.3°C).
The month with the lowest average high temperature is January (6.8°C).

  • Average low temperature in September: 11.3°C

The month with the highest average low temperature is August (13.8°C).
The coldest month (with the lowest average low temperature) is January (2.2°C).

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Average pressure in September
London, United Kingdom

Average pressure in September - London, 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 (1010.6mbar).

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Average wind speed in September
London, United Kingdom

Average wind speed in September - London, United Kingdom
  • Average wind speed in September: 12.6km/h

The windiest month (with the highest average wind speed) is February (17.3km/h).
The calmest month (with the lowest average wind speed) is September (12.6km/h).

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Average humidity in September
London, United Kingdom

Average humidity in September - London, United Kingdom
  • Average humidity in September: 76%

The month with the highest relative humidity is December (88%).
The month with the lowest relative humidity is August (72%).

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Average rainfall in September
London, United Kingdom

Average rainfall in September - London, United Kingdom
  • Average rainfall in September: 26mm

The wettest month (with the highest rainfall) is June (45mm).
The driest month (with the least rainfall) is April (22mm).

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Average rainfall days in September
London, United Kingdom

Average rainfall days in September - London, United Kingdom
  • Average rainfall days in September: 9.8 days

The month with the highest number of rainy days is July (16.5 days).
The month with the least rainy days is September (9.8 days).

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Average snowfall in September
London, United Kingdom

Average snowfall in September - London, United Kingdom
  • Average snowfall in September: 0mm

The month with the highest snowfall is February (16mm).
The months with the least snowfall are May, June, July, August, September and October (0mm).

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Average snowfall days in September
London, United Kingdom

Average snowfall days in September - London, United Kingdom
  • Average snowfall days in September: 0 days

The month with the highest number of snowfall days is February (2.5 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).

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Average daylight in September /
Average sunshine in September
London, United Kingdom

Average daylight in September / Average sunshine in September - London, United Kingdom
  • Average daylight in September: 12h and 4min

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 1min

The month with the most sunshine is August (Average sunshine: 7h and 54min).
The month with the least sunshine is February (Average sunshine: 3h and 36min).

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Average sunshine days in September
London, United Kingdom

Average sunshine days in September - London, United Kingdom
  • Average sunshine days in September: 18.1 days

The month with the most sunshine days is September (18.1 days).
The month with the least sunshine days is June (12.2 days).

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Average UV index in September
London, United Kingdom

Average UV index in September - London, 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).

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Average cloud cover in September
London, United Kingdom

Average cloud cover in September - London, United Kingdom
  • Average cloud cover in September: 49

The month with the most cloud cover is February (Cloud cover 61).
The month with the least cloud cover is September (Cloud cover 49).

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Average visibility in September
London, United Kingdom

Average visibility in September - London, United Kingdom
  • Average visibility in September: 8km

The months with the highest visibility are January, February, March, April, May, June, July, August, October and December (9km).
The months with the lowest visibility are September and November (8km).

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London, United Kingdom

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