September Weather in London, Canada

Last updated: June 18, 2025

In London, Canada, the average temperature in September hovers around 17°C (64°F). Expect temperatures to vary significantly, with a minimum of 1°C (34°F) and a maximum reaching 32°C (90°F). Prepare for 86 mm (3.4 in) of precipitation spread over about 11 days, and don’t forget to account for the high humidity at an average of 81%!

September Temperature in London

In September, in London, the average temperature is 17°C (64°F). The maximum can reach 32°C (90°F), and the minimum can be as low as 1°C (34°F). Be prepared for a wide range of temperatures, making it essential to pack for both warm and cool conditions during your travels.

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 17°C (64°F), with highs reaching up to 32°C (90°F) and lows dropping to around 1°C (34°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 86 mm (3.4 in), spread over 11 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 86 mm (3.4 inches) of precipitation spread over approximately 11 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 81%. With an average temperature of 17°C (64°F), this humidity feels like walking through a warm mist, enveloping you in a sticky embrace that can quickly lead to discomfort during long sightseeing excursions.

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 81%, 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 8, which corresponds to a very high Exposure Category. This means that the time to burn is only 15 minutes. For more detailed information, you can refer to 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 8, 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	-4°C (25°F)	74 mm (2.9 inches)	90%	low
February Weather	-3°C (26°F)	78 mm (3.1 inches)	90%	moderate
March Weather	1°C (34°F)	78 mm (3.1 inches)	87%	moderate
April Weather	7°C (44°F)	105 mm (4.1 inches)	87%	very high
May Weather	14°C (57°F)	104 mm (4.1 inches)	82%	very high
June Weather	19°C (67°F)	105 mm (4.1 inches)	81%	very high
July Weather	22°C (72°F)	97 mm (3.8 inches)	79%	very high
August Weather	21°C (70°F)	108 mm (4.2 inches)	80%	very high
September Weather	17°C (64°F)	86 mm (3.4 inches)	81%	very high
October Weather	11°C (53°F)	124 mm (4.9 inches)	84%	moderate
November Weather	3°C (38°F)	91 mm (3.6 inches)	88%	moderate
December Weather	0°C (31°F)	72 mm (2.8 inches)	87%	low