September Weather in London, United States

Last updated: June 24, 2025

In September, the average temperature in London, United States hovers around 24°C (76°F). You can expect a pleasant range, with minimums dipping to 9°C (48°F) and maximums soaring up to 36°C (97°F). While you enjoy the warm weather, be prepared for approximately 65 mm (2.6 in) of rainfall spread over 6 days, resulting in an average humidity of 59%.

September Temperature in London

In September in London, the average temperature is 24°C (76°F). Maximum can reach 36°C (97°F), and minimum can be as low as 9°C (48°F). This makes London a great destination for travelers looking to enjoy mild weather with the possibility of warm days and cooler evenings.

September Weather in London: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in London, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In London, September typically has an average temperature of 24°C (76°F), with highs reaching up to 36°C (97°F) and lows dropping to around 9°C (48°F).

Data source: Temperature data for London generated using information from the Copernicus Climate Change Service.

September Precipitation in London

In London, in September, the precipitation amount is 65 mm (2.6 in) over a period of 6 days.

September Precipitation Trends in London

The chart displays monthly precipitation patterns in London, with values for each month alongside September’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how September’s conditions compare to those of other months. In London, September typically receives around 65 mm (2.6 inches) of precipitation spread over approximately 6 days.

Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.

Choose your preferred precipitation unit

Millimeters (mm) Inches (in)

September Humidity in London

In London in September humidity is 59%. With an average temperature of 24°C (76°F), this humidity feels like a comfortable, refreshing embrace, making it ideal for leisurely strolls and outdoor explorations.

September Average Humidity in London

This chart illustrates the average monthly humidity levels in London, with September’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In September, average humidity in London is approximately 59%, offering insight into how humid the weather typically is during this month.

Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in London

In London in September, the maximum UV index is 9, which corresponds to a very high Exposure Category. The time to burn is just 15 minutes, so it's essential to take precautions. For detailed information, you can check the Hourly UV Index in London.

Maximum UV Index Levels in London for September

The chart shows the monthly maximum UV Index (UVI) for London in September, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues. In September, the maximum UV index in London typically reaches 9, which falls under the very high exposure category.

Data source: London September UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

Extreme (11+): Avoid the sun, stay in shade.
Very High (8-10): Limit sun exposure.
High (6-7): Use SPF 30+ and protective clothing.
Moderate (3-5): Midday shade recommended.
Low (0-2): No protection needed.

How September Weather in London Compares to Other Months

Weather in London varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in London, focusing on differences in temperature, rainfall, humidity, and UV levels.

This table compares monthly weather conditions in London, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	5°C (41°F)	88 mm (3.4 inches)	82%	moderate
February Weather	7°C (44°F)	135 mm (5.3 inches)	79%	high
March Weather	12°C (54°F)	140 mm (5.5 inches)	77%	very high
April Weather	15°C (60°F)	150 mm (5.9 inches)	78%	very high
May Weather	21°C (70°F)	198 mm (7.8 inches)	82%	very high
June Weather	26°C (78°F)	122 mm (4.8 inches)	81%	extreme
July Weather	27°C (82°F)	86 mm (3.4 inches)	75%	extreme
August Weather	26°C (80°F)	127 mm (5.0 inches)	61%	very high
September Weather	24°C (76°F)	65 mm (2.6 inches)	59%	very high
October Weather	17°C (64°F)	103 mm (4.1 inches)	69%	high
November Weather	10°C (51°F)	88 mm (3.4 inches)	82%	moderate
December Weather	8°C (46°F)	100 mm (3.9 inches)	87%	moderate