September weather forecast and climate
London, United Kingdom

The large Thames river in London overlooking the Westminster Palace and the Big Ben clock tower in London, United Kingdom, on a cloudy evening after sunset
The large Thames river in London overlooking the Westminster Palace and the Big Ben clock tower in London, United Kingdom, on a cloudy evening after sunset
The first month of the autumn, September, is still a comfortable month in London, United Kingdom, with average temperature fluctuating between 11.3°C (52.3°F) and 19°C (66.2°F).

Temperature

In London, United Kingdom, the average high-temperature is practically the same as in August - a comfortable 19°C (66.2°F). The average low-temperature, is 11.3°C (52.3°F).

Humidity

The average relative humidity in September is 76%.

Rainfall

In London, during 9.8 rainfall days, 26mm (1.02") of precipitation is typically accumulated. Throughout the year, there are 151.7 rainfall days, and 370mm (14.57") of precipitation is accumulated.

Snowfall

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

Daylight

The average length of the day is 12.6h.

Sunshine

In London, United Kingdom, the average sunshine is 7.1h.

UV index

In London, the average daily maximum UV index in September is 4. A UV Index reading of 3 to 5 represents a moderate threat to health from unsafe exposure to the UV radiation for the average person.
Note: In September, the average maximum UV index of 4 translate into the following recommendations:
Take precautions - Protection against sunburn is recommended. The solar radiation is most powerful near the mid-day, so the exposure to the direct Sun should be reduced accordingly. Sun-protective clothing, a long-sleeved shirt and pants, a wide-brimmed hat, and UVA and UVB-blocking sunglasses are particularly helpful in blocking UV radiation's harmful effects.

What is the temperature in September in London?

The average high-temperature, in September, in London, United Kingdom, is 19°C (66.2°F), while the average low-temperature is 11.3°C (52.3°F).

What is the average humidity in September in London?

In September, the average relative humidity is 76%.

How much does it rain in London in September?

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?

May through October are months without snowfall.

What is the average length of the day in September in London?

In September, the average length of the day in London is 12.6h.

How many hours of sunshine does London have in September?

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

What is the UV index intensity in September in London?

In September, the average daily maximum UV index is 4. A UV Index estimate of 3 to 5 represents a medium health risk from unsafe exposure to the Sun's UV rays.
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).

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%).

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).

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).

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

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

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).
Months with the least snowfall days are May, June, July, August, September and October (0 days).

Average daylight in September / Average sunshine in September - London, United Kingdom
  • Average daylight in September: 12.6h

The month with the longest days is June (Average daylight: 16.5h).
The month with the shortest days is December (Average daylight: 7.9h).

  • Average sunshine in September: 7.1h

The month with the most sunshine is August (Average sunshine: 7.9h).
The month with the least sunshine is February (Average sunshine: 3.6h).

Average UV index in September - London, United Kingdom
  • Average UV index in September: 4

Months with the highest UV index are June and July (UV index 5).
Months with the lowest UV index are January, February, November and December (UV index 2).