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September Weather in Merton, United Kingdom

Last updated: August 27, 2025

In September, the average temperature in Merton, United Kingdom is a pleasant 14°C (58°F). Expect a range from a cool 4°C (40°F) at night to a warm 27°C (81°F) during the day. Over the month, 75 mm (2.9 in) of precipitation is anticipated, spread across 11 days, while the air maintains an average humidity of 79%.

September Temperature in Merton

In September in Merton, the average temperature is 14°C (58°F). Maximum can reach 27°C (81°F) and minimum can be as low as 4°C (40°F). This makes it an ideal time for travelers to enjoy pleasant weather while exploring all that Merton has to offer.

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

The chart illustrates September temperature patterns in Merton, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Merton, September typically has an average temperature of 14°C (58°F), with highs reaching up to 27°C (81°F) and lows dropping to around 4°C (40°F).
JanFebMarAprMayJunJulAugSepOctNovDec434445485359616158534846
Data source: Temperature data for Merton generated using information from the Copernicus Climate Change Service.
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The average of daily temperatures (24 hours) calculated across all days in the month.

September Precipitation in Merton

In Merton in September, the precipitation amount is 75 mm (2.9 in) over the course of 11 days.

September Precipitation Trends in Merton

The chart displays monthly precipitation patterns in Merton, 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 Merton, September typically receives around 75 mm (2.9 inches) of precipitation spread over approximately 11 days.
JanFebMarAprMayJunJulAugSepOctNovDec70808851688375827510790122
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Merton

In Merton in September, humidity is 79%. With an average temperature of 14°C (58°F), this humidity feels like an oppressive blanket wrapped around you, making even the mild temperatures feel heavier and more stifling for traveling.

September Average Humidity in Merton

This chart illustrates the average monthly humidity levels in Merton, 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 Merton is approximately 79%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec89%88%86%84%80%80%70%73%79%89%90%89%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Merton

In Merton in September, the maximum UV index is 6, which corresponds to a high Exposure Category. The time to burn is approximately 25 minutes. To find the hourly UV index in Merton, you can refer to this Hourly UV Index in Merton.

Maximum UV Index Levels in Merton for September

The chart shows the monthly maximum UV Index (UVI) for Merton 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 Merton typically reaches 6, which falls under the high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec124678876421
Data source: Merton 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 Merton Compares to Other Months

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

This table compares monthly weather conditions in Merton, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather6°C (43°F)70 mm (2.7 inches)88%low
February Weather7°C (44°F)80 mm (3.2 inches)88%low
March Weather7°C (45°F)88 mm (3.5 inches)86%moderate
April Weather9°C (49°F)51 mm (2.0 inches)84%high
May Weather11°C (53°F)68 mm (2.7 inches)80%high
June Weather15°C (59°F)83 mm (3.3 inches)80%very high
July Weather16°C (62°F)75 mm (3.0 inches)70%very high
August Weather16°C (61°F)82 mm (3.2 inches)73%high
September Weather14°C (58°F)75 mm (2.9 inches)79%high
October Weather12°C (53°F)107 mm (4.2 inches)89%moderate
November Weather9°C (48°F)90 mm (3.6 inches)90%low
December Weather8°C (46°F)122 mm (4.8 inches)89%low

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