Last updated: March 17, 2025
In September, the City of London experiences a delightful transition into autumn, characterized by a maximum temperature reaching up to 28°C (83°F) and an average of 15°C (60°F), providing an inviting climate for outdoor activities. However, temperatures can dip as low as 4°C (40°F), reminding residents of the approaching cooler months. The city sees about 45 mm (1.8 in) of precipitation across 9 days, contributing to a humidity level of 80%, which can make mornings feel particularly brisk. This blend of warmth and moisture makes September a captivating period in London, perfect for embracing the vibrant hues of fall.
As September rolls in, the City of London begins to shed the sweltering heat of summer, showcasing a noticeable shift in temperatures. The month greets residents with a minimum temperature of 4°C (40°F), while the average sits at a comfortable 15°C (60°F), making it a pleasant time for outdoor activities. Days can still be warm, peaking at a max of 28°C (83°F), inviting a blend of summery warmth and early autumn crispness. This transition signals a gradual cooling trend as the city moves into the fall months, with temperatures steadily declining from the highs of summer towards the cooler October averages. September serves as a sweet goodbye to summer, with just enough warmth to enjoy the outdoors before the chill of autumn sets in.
September in the City of London typically sees moderate rainfall, with an average precipitation of 45 mm (1.8 in) spread across about 9 days. This marks a slight decrease from the wetter summer months, where August recorded 72 mm (2.8 in), suggesting that the city begins transitioning into its drier autumn season. As temperatures cool, the frequency and intensity of showers gently taper off, creating a refreshing atmosphere ideal for those enjoying early autumn strolls. With rainfall peaking in the subsequent month of October, marked by 81 mm (3.2 in), September serves as a reminder of the shifting seasons, balancing pleasant weather with a hint of seasonal change.
As September arrives in London, the city's humidity rises to 80%, marking a subtle yet significant shift from the drier summer months of July and August, where humidity levels dropped to 76% and 73%, respectively. This increase signals the gradual transition to wetter autumn weather, reminiscent of the higher humidity levels experienced earlier in the year, particularly in January and February, when moisture levels hovered around 91% and 89%. September’s humidity stands as a reminder of the shifting seasons, bridging the warm, often balmy sensations of summer with the cooler, more damp conditions that follow in October and beyond, where humidity returns to 89%. Overall, the trend showcases London's characteristic humidity rollercoaster, fluctuating seasonally but always retaining a damp essence.
As September rolls into the City of London, the UV Index settles at 6, placing it in the high exposure category. This signals a notable shift from the intense sun of summer, where July and June reached a scorching 8. With a burn time of 25 minutes, it’s essential to remain cautious and protect your skin during outdoor activities, even as temperatures begin to drop. Transitioning from the summer months, September's UV levels still require attention, particularly as many people enjoy the lingering warmth of early autumn. Stay informed about how much sun you are getting and plan accordingly to enjoy the outdoors safely. For more details, visit the City of London UV Index.
UV Risk Categories
September in the City of London brings a delightful transition, showcasing 300 hours of sunshine that gently herald the arrival of autumn. This month continues the pattern of warmer days and longer daylight experienced during the vibrant summer months of July and August, where the city basked in 405 and 372 hours of sunlight, respectively. Although the sun's embrace begins to wane, September's ample hours still surpass those of the cooler months ahead, like October and November, which drop to 240 and 142 hours. This trend highlights the lingering warmth of early fall, inviting Londoners and visitors alike to enjoy the city's charm bathed in golden light before the shorter days settle in.
September in the City of London continues the trend of fluctuating chances for sunny weather as summer draws to a close. With a 29% chance of sunshine, this month mirrors the levels seen in both July and August, suggesting that while the sun may make occasional appearances, it's less reliable than in the peak summer months. Following the higher likelihood of clear skies in April, when the chances peaked at 49%, September feels a bit more temperamental, sharing its sunshine probabilities with notable months like March and June. As autumn approaches, Londoners might want to seize any sunny moments while they can, though the lingering warmth of summer occasionally brightens up this transitional month.
As summer transitions into autumn, September in the City of London sees a notable reduction in daylight, with an average of 12 hours illuminating the days. Following the sun-soaked months of June and July, which bask in 16 hours of daylight, September marks a gentle decline as daylight begins to retreat. This gradual waning is reminiscent of the vibrant colors of fall that start to emerge, bridging the gap between the bright 15 hours of daylight in May and the more subdued 10 hours expected in October. The shift signifies not just a change in light but also a prelude to the cozy embrace of autumn, inviting residents and visitors alike to savor the last warm evenings of the year before the darker months settle in.
As September unfolds in the City of London, the average wind speed dips to a gentle 3.2 m/s (7 mph), marking a notable decline from the summer months. This shift signals a transition from the warmer breezes of July and August, which hovered around 3.3 m/s (7 mph) and 3.8 m/s (8 mph), respectively. By the time October arrives, however, the winds pick up again, rising to 4.3 m/s (10 mph), suggesting that autumn's brisk air is on the horizon. Overall, September's calmer winds foster a serene atmosphere, preparing the city for the invigorating gusts that follow in the subsequent months.
The weather in City of London changes throughout the year, offering a unique experience in each season. Below is a month-by-month comparison of September's weather with other months, highlighting differences in temperature, precipitation, and other key factors. Click on each section to discover seasonal trends in City of London and find detailed weather information for every month.
In September, the weather is generally milder, with temperatures ranging from a minimum of 4°C (40°F) to a maximum of 28°C (83°F) and an average of 15°C (60°F). The month experiences about 45 mm (1.8 in) of precipitation over 9 days, accompanied by a relative humidity of 80%. In contrast, January brings much cooler temperatures, with a minimum of -5°C (24°F), an average of 5°C (41°F), and a maximum of 14°C (58°F). While precipitation slightly increases to 54 mm (2.1 in) over the same number of days, the humidity also rises to 91%, contributing to a chillier and more damp atmosphere. For more detailed information, check out the City of London weather in January.
When comparing the weather between September and February, it's evident that September offers milder temperatures with an average of 15°C (60°F) and maximums reaching up to 28°C (83°F). In contrast, February is significantly colder, with average temperatures of just 6°C (43°F) and minimums plunging down to -7°C (21°F). Both months experience a fair amount of precipitation, with February slightly ahead at 52 mm (2.0 in) compared to September's 45 mm (1.8 in), and February also has more rainy days, with 11 compared to September's 9. Additionally, the humidity is higher in February at 89% versus September's 80%. For those interested in more detailed weather information, check out City of London weather in February.
September and March present contrasting weather patterns. In September, temperatures range from a cool 4°C (40°F) to a warm 28°C (83°F), averaging around 15°C (60°F), with relatively lower humidity at about 80% and 45 mm of precipitation over 9 days. In contrast, March experiences colder conditions, with temperatures dipping as low as -5°C (23°F) and peaking at 22°C (72°F), averaging only 8°C (46°F). The month also sees slightly higher humidity at 86% and more rainfall, totaling 52 mm over 13 days. For a more detailed look at the weather in March, you can check City of London weather in March.
When comparing the weather in September and April, notable differences emerge in temperature and precipitation. September boasts a milder average temperature of 15°C (60°F), with daytime highs reaching up to 28°C (83°F), while April has a cooler average of 10°C (49°F) and highs of 26°C (80°F). Although both months experience some rainfall, September sees slightly more precipitation at 45 mm (1.8 in) over 9 days, compared to April's 32 mm (1.3 in) over 7 days. Additionally, humidity levels are similar, with April being slightly more humid at 85% versus September's 80%. For a detailed look at April weather patterns, check this link: City of London weather in April.
In comparing the weather of September and May, we find a noticeable difference in temperature and precipitation levels. September tends to be warmer, with average temperatures ranging from a minimum of 4°C (40°F) to a maximum of 28°C (83°F), while May averages between 1°C (34°F) and 25°C (78°F). Additionally, September experiences slightly less rainfall, with 45 mm (1.8 in) over about 9 days, compared to May's 63 mm (2.5 in) across 10 days. Humidity levels are similar in both months, hovering around 80% in September and 82% in May. For a detailed look at May's weather specifics, visit City of London weather in May.
September and June present distinct weather patterns in terms of temperature and precipitation. In September, temperatures range from a minimum of 4°C (40°F) to a maximum of 28°C (83°F), averaging around 15°C (60°F). The month experiences about 45 mm (1.8 in) of precipitation over 9 days, with humidity levels at 80%. In contrast, June offers warmer conditions, with temperatures ranging from 7°C (45°F) to a high of 32°C (89°F) and an average of 17°C (62°F). This month is slightly wetter, with 77 mm (3.0 in) of rainfall spread across 8 days, while humidity is slightly higher at 81%. For more detailed insights, check City of London weather in June.
In comparing the weather between September and July, September generally offers a wider range of temperatures, with minimums dipping to 4°C (40°F) and maximums reaching 28°C (83°F), averaging around 15°C (60°F). In contrast, July is typically warmer, with minimum temperatures starting at 9°C (49°F) and reaching highs of up to 36°C (97°F), averaging 18°C (65°F). While September has slightly lower precipitation at 45 mm (1.8 in) over 9 days, July sees more rainfall at 64 mm (2.5 in) over 11 days, though both months experience relatively high humidity, with September at 80% and July at 76%. For more detailed weather patterns, you can check the following link: City of London weather in July.
In comparing the weather between August and September, it's evident that September experiences cooler temperatures, with a minimum of 4°C (40°F) compared to August's minimum of 8°C (47°F). The average temperature in September is also lower at 15°C (60°F), while August boasts a warmer average of 18°C (64°F). However, September allows for higher maximum temperatures, reaching up to 28°C (83°F) compared to August's maximum of 34°C (94°F). Precipitation is higher in August, with 72 mm (2.8 in) over 12 days, versus September's 45 mm (1.8 in) over 9 days. Notably, September has higher humidity levels at 80% compared to August's 73%, which can make the cooler temperatures feel more oppressive. For more detailed weather information, you can check out the City of London weather in August.
September and October exhibit notable differences in weather patterns. In September, temperatures range from a minimum of 4°C (40°F) to a maximum of 28°C (83°F), with an average temperature of 15°C (60°F). The month sees a total precipitation of 45 mm (1.8 in) over 9 days, with humidity levels at 80%. In contrast, October experiences cooler temperatures, with a minimum of 1°C (34°F) and a maximum of 23°C (73°F), averaging around 12°C (54°F). This month also brings increased rainfall, totaling 81 mm (3.2 in) across 12 days and a rise in humidity to 89%. For more details, you can check out the City of London weather in October.
September and November present contrasting weather conditions. In September, temperatures range from a brisk 4°C (40°F) at night to a warm 28°C (83°F) during the day, with an average of 15°C (60°F). This month sees about 45 mm (1.8 in) of rain over 9 days, accompanied by a humidity level of 80%. In contrast, November experiences cooler temperatures, with a minimum of -2°C (28°F) and a maximum of 17°C (62°F), averaging around 8°C (47°F). Precipitation slightly increases to 48 mm (1.9 in) over 10 days, and humidity rises to 92%. For more detailed information on November conditions, check out the City of London weather in November.
September and December present contrasting weather profiles. In September, temperatures range from a mild minimum of 4°C (40°F) to a maximum of 28°C (83°F), with an average of 15°C (60°F). The month sees around 45 mm (1.8 in) of precipitation over approximately 9 days and a humidity level of 80%. In stark contrast, December experiences much colder temperatures, with a minimum of -4°C (25°F) and a maximum of 14°C (58°F), averaging around 6°C (44°F). Precipitation increases to 84 mm (3.3 in) spread across 14 days, and humidity rises to 92%. For a more detailed look at December weather, visit City of London weather in December.
As September unfolds in the City of London, the weather begins to shift, offering a blend of warmth and the crispness of early autumn. Unlike the sizzling summer months, where temperatures often soar, September boasts a more temperate atmosphere, with an average that encourages outdoor activities while keeping the evenings refreshingly cool. With about nine days of rain, the month serves as a reminder that the transition to fall is upon us, contributing to a humidity level of 80% that coats the air in a gentle embrace. This unique pattern of mild days and intermittent showers sets September apart from the rest of the year, marking it as a time of change and anticipation. For further insights into the seasonal patterns, visit City of London Climate.