September Weather in Southampton, United Kingdom

Last updated: March 17, 2025

September in Southampton, United Kingdom, is marked by a delightful blend of warm and cool temperatures. With a maximum reaching 28°C (82°F) and an average of 15°C (59°F), the month offers a comfortable climate for outdoor activities. However, nighttime can dip down to a brisk 3°C (37°F), reminding residents that autumn is on the horizon. Rainfall of 47 mm (1.9 in) over 9 days keeps the city lush, while an average humidity of 82% adds to the freshness of this transitional month. Embrace the charm of Southampton as summer gracefully fades into fall!

September Temperature in Southampton

As September rolls into Southampton, temperatures begin to transition from the lingering warmth of summer to the cooler embrace of autumn. The month showcases a delightful range, with minimums around 3°C (37°F) that hint at the upcoming chill, while averages hover at a comfortable 15°C (59°F), providing a pleasant backdrop for outdoor activities. Daytime highs can still reach a balmy 28°C (82°F), allowing for a few last sunny escapes before the colder months set in. This month reflects a shift in the weather, with evenings becoming crisper and the air refreshing, making September an ideal time to explore the city or enjoy its scenic coastal views.

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

The chart illustrates September temperature patterns in Southampton, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends.
JanFebMarAprMayJunJulAugSepOctNovDec414346495561656359534744
Data source: Temperature data for Southampton generated using information from the Copernicus Climate Change Service.
Choose your preferred temperature unit
The average of daily temperatures (24 hours) calculated across all days in the month.

September Precipitation in Southampton

In September, Southampton experiences a transition as summer fades into autumn, reflected in its precipitation patterns. With an average rainfall of 47 mm (1.9 in) over approximately 9 days, this month sees a noticeable decrease in rainfall compared to the wetter summer months of June and August, which recorded 83 mm (3.3 in) and 71 mm (2.8 in) respectively. This reduction signals a shift towards drier conditions as autumn approaches, though occasional showers still punctuate the month, reminding residents of the impending seasonal changes. Following September's relatively moderate rainfall, October typically reverts to a trend of higher precipitation, setting the stage for the wetter months ahead.

September Precipitation Trends in Southampton

The chart displays monthly precipitation patterns in Southampton, 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.
JanFebMarAprMayJunJulAugSepOctNovDec5260673970835871471036593
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
Choose your preferred precipitation unit

September Humidity in Southampton

As summer fades into autumn, September in Southampton witnesses a transition in humidity levels, peaking at 82%. This marks a noticeable shift from the drier months of July and August, where humidity dipped to 71% and 76% respectively. The easing warmth of late summer gives way to an increase in moisture in the air, signaling the onset of the wetter season. Following September, humidity rises sharply in October, reaching 90%, and continues to soar, staying high throughout the winter months. This pattern underscores a distinct trend in Southampton's climate, where the late summer months invite a brief respite from humidity before the city braces for the dampness that characterizes the fall and winter.

September Average Humidity in Southampton

This chart illustrates the average monthly humidity levels in Southampton, with September's data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, allowing you to see how September's humidity levels compare to other months.
JanFebMarAprMayJunJulAugSepOctNovDec91%89%86%85%79%81%71%76%82%91%92%92%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Southampton

As summer transitions to autumn, September in Southampton sees a UV Index of 6, placing it in the high exposure category. This means residents and visitors should be cautious while enjoying outdoor activities, as the potential to burn occurs within just 25 minutes of unprotected sun exposure. While slightly lower than the peak summer months of June and July, which both boasted a very high index of 8, September still demands attention to sun safety. It’s a vibrant time to revel in the outdoors, but don’t forget to apply sunscreen and seek shade when the sun is at its strongest. For more detailed information on UV levels throughout the year, visit Southampton UV Index.

Maximum UV Index Levels in Southampton for September

The chart shows the monthly maximum UV Index (UVI) for Southampton 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.
JanFebMarAprMayJunJulAugSepOctNovDec124678876421
Data source: Southampton 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.

September Sunshine in Southampton

September brings a gentle transition in Southampton, UK, as the summer sun begins to wane but still offers a respectable 287 hours of sunshine. This month reflects a notable decline from the sun-soaked glory of July and August, which boast 395 and 354 hours, respectively. However, September thrives with warmth, providing a beautiful backdrop for outdoor activities as the vibrant colors of early autumn emerge. As the year progresses towards the colder months, with October dipping to 233 hours of sunshine, September holds onto the lingering rays of summer, marking a perfect time to enjoy the city's parks and waterfront before the shorter days take hold.

Monthly Sunshine Duration in Southampton: September Highlighted

The September sunshine duration represents the total number of hours Southampton experiences direct sunlight during the month of September, excluding cloudy or obstructed periods. This chart compares the sunshine duration of September with the other months of the year.
JanFebMarAprMayJunJulAugSepOctNovDec98h138h193h316h384h373h395h354h287h233h141h108h
Data source: Southampton September Sunshine duration data generated using information from the Copernicus Climate Change Service.

Chance of Sun in Southampton During September

As summer winds down, September in Southampton offers a modest 30% chance of sunny weather. This marks a slight increase compared to the summer months, reflecting a transitional period where the warmth of August gives way to the cooler embrace of autumn. While the optimism for sunny days is tempered by a dip from the more abundant sunshine earlier in the year, September still holds its own in the grand scheme of the seasons. The trends reveal a month that balances the last vestiges of summer with early autumn, making it a charming time for outdoor activities—perfect for soaking in the fleeting rays before the clouds take over.

Percentage of Sunny Days in September in Southampton

The chart illustrates the percentage of sunny days in Southampton throughout the year, with September highlighted. It highlights the variation in sunshine across each month and provides an overview of the typical frequency of sunny days, offering insights into how often Southampton experiences clear skies throughout the year.
JanFebMarAprMayJunJulAugSepOctNovDec22%25%33%55%36%29%38%28%30%27%34%21%
Data source: Southampton September chance of sun data, generated using information from the Copernicus Climate Change Service.

Daylight Hours in Southampton in September

As autumn approaches, September in Southampton ushers in a subtle shift in daylight duration, providing about 12 hours of daylight. This marks a gradual decline from the summer peak of 16 hours in June, as the days become noticeably shorter. Interestingly, September retains more light than its preceding month, August, which boasts 14 hours of daylight. This transitional month serves as a gentle reminder of the fading summer sun, as it gracefully navigates towards the shorter days of October, where daylight dips to 10 hours. The pattern reflects the natural ebb and flow of the seasons, inviting residents to cherish the last warm days before winter’s approach.

Average Daylight Hours in Southampton for September

The chart illustrates the variation in daylight duration in Southampton throughout the year, with September highlighted. It shows the monthly changes in daylight hours, calculated by summing the hours between sunrise and sunset.
JanFebMarAprMayJunJulAugSepOctNovDec8h 28m10h 1m11h 55m13h 52m15h 33m16h 26m15h 58m14h 27m12h 34m10h 38m8h 54m7h 59m
Data source: Southampton daylight hours, calculated by summing the hours between sunrise and sunset for each day.

September Winds in Southampton

As September unfolds in Southampton, the average wind speed settles at 3.5 m/s (8 mph), a gentle breeze that provides a pleasant backdrop to the shifting season. This marks a slight decrease from the summer months, reflecting the calming transition towards autumn. Notably, September's wind speed is part of a broader trend where the warmer months typically exhibit lighter winds, with speeds averaging around 3.4 to 4.5 m/s during the summer. As the year progresses, the winds begin to pick up again in October, reaching 4.5 m/s (10 mph). This rhythmic fluctuation in wind speed not only signals the changing weather but also enhances the charm of Southampton as it prepares for the crisp days ahead.

Average September Wind Speed in Southampton

The chart displays monthly wind speed patterns in Southampton, with values for each month shown alongside September's data, which is highlighted for easy comparison. It illustrates the average wind speed, offering insights into how September's wind conditions compare to the rest of the year.
JanFebMarAprMayJunJulAugSepOctNovDec4.65.24.53.44.53.23.43.83.5 m/s4.53.84.6
Data source: Southampton September wind data, generated using information from the Copernicus Climate Change Service.

How September Weather in Southampton Compares to Other Months

The weather in Southampton 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 Southampton and find detailed weather information for every month.

In comparing the weather of September and January, we see a marked contrast in temperatures and conditions. September boasts a pleasant average of 15°C (59°F) with daytime highs reaching up to 28°C (82°F), while January brings cooler temperatures, averaging only 5°C (42°F) and maxing out at 14°C (57°F). Precipitation is slightly higher in January, at 52 mm (2.1 in) over 10 days, compared to September's 47 mm (1.9 in) over 9 days, though January's humidity is notably higher at 91% versus September's 82%. For more detailed insights, check out Southampton weather in January.

In comparing the weather of September and February, we observe notable differences in temperature and humidity. September features a more moderate climate with temperatures ranging from a minimum of 3°C (37°F) to a maximum of 28°C (82°F), averaging 15°C (59°F). This month experiences 47 mm (1.9 in) of precipitation over about 9 days, with humidity around 82%. In contrast, February is cooler, with temperatures ranging from a minimum of -6°C (21°F) to a maximum of 16°C (62°F), averaging 6°C (44°F). This winter month sees slightly increased precipitation of 60 mm (2.4 in) over 11 days and higher humidity at 89%. For more detailed insights into February weather, visit Southampton weather in February.

September and March present contrasting weather patterns, showcasing the transition from late summer to early spring. In September, temperatures range from a mild 3°C (37°F) at night to a warm 28°C (82°F) during the day, with an average of 15°C (59°F). This month experiences 47 mm (1.9 in) of precipitation over about 9 days, accompanied by relatively high humidity at 82%. In contrast, March sees cooler temperatures, dipping as low as -6°C (22°F) and reaching a maximum of 20°C (68°F), with an average temperature of 8°C (46°F). Precipitation is slightly higher at 67 mm (2.6 in) over 13 days, with humidity rising to 86%. The shift from warm September days to the chill of March highlights the seasonal changes in Southampton’s climate, as detailed in more depth in the article linked here: Southampton weather in March.

In September, the weather tends to be warmer than in April, with average temperatures ranging from a minimum of 3°C (37°F) to a maximum of 28°C (82°F). This month sees approximately 47 mm (1.9 in) of precipitation over about 9 days, accompanied by a humidity level of 82%. In contrast, April experiences cooler temperatures, with a minimum of -3°C (27°F) and a maximum of 24°C (76°F), along with slightly less precipitation at 39 mm (1.5 in) over 7 days, and humidity of 85%. For more details on the weather during this spring month, you can check Southampton weather in April.

In comparing the weather between September and May, September offers a wider range of temperatures, with minimums around 3°C (37°F) and maximums reaching 28°C (82°F), resulting in an average of 15°C (59°F). In contrast, May has slightly lower overall temperatures, with minimums at 1°C (33°F) and maximums up to 25°C (77°F), averaging at 13°C (55°F). While September experiences about 47 mm (1.9 in) of precipitation over 9 days, May sees a bit more rain, with 70 mm (2.8 in) over 10 days, although the humidity is marginally lower in May at 79% compared to 82% in September. For those interested in more detailed weather patterns for May, you can check Southampton weather in May.

September and June present distinct weather characteristics, reflecting the transition from summer to autumn. In September, temperatures range from a cooler minimum of 3°C (37°F) to a maximum of 28°C (82°F), with an average of 15°C (59°F). This month sees about 47 mm (1.9 in) of precipitation over 9 days, coupled with relatively high humidity at 82%. In contrast, June offers slightly warmer conditions, with minimum temperatures starting at 6°C (43°F) and peaking at 30°C (87°F), averaging 16°C (61°F). Additionally, June experiences increased precipitation at 83 mm (3.3 in) across 10 days, with humidity just slightly lower at 80%. For more detailed information, check Southampton weather in June.

In comparing the weather between September and July, September typically features cooler temperatures, with an average of 15°C (59°F) and a maximum of 28°C (82°F), while July tends to be warmer overall, boasting an average of 18°C (65°F) and reaching up to 31°C (88°F). Humidity levels are higher in September at 82%, compared to July's 71%, which may make the warmer days feel more comfortable as they are less humid. Both months experience a fair amount of precipitation, with September receiving about 47 mm over 9 days and July slightly more at 58 mm over 11 days. For a more detailed look at July's weather conditions, you can refer to Southampton weather in July.

In September, the weather shows a notable cooling trend compared to August, with minimum temperatures dropping to 3°C (37°F) from August's 7°C (45°F) and average temperatures decreasing from 17°C (63°F) to 15°C (59°F). The maximum temperature also sees a decline, reaching 28°C (82°F) in September compared to 31°C (89°F) in August. Additionally, September experiences slightly less precipitation at 47 mm (1.9 in) over 9 days, compared to August's 71 mm (2.8 in) spread over 12 days, despite a higher humidity level of 82% in September versus 76% in August. For a detailed look at August's weather specifically, check out Southampton weather in August.

September typically boasts warmer temperatures, with averages around 15°C (59°F) and highs reaching up to 28°C (82°F). In contrast, October sees a notable drop, with average temperatures declining to 12°C (54°F) and maximums capped at 21°C (71°F). Additionally, October experiences significantly more precipitation, totaling 103 mm (4.1 in) over 13 days compared to September's 47 mm (1.9 in) over just 9 days. The humidity also rises slightly, making October feel a bit wetter at 90% compared to September’s 82%. For more details on October's weather, check Southampton weather in October.

In September, temperatures in Southampton typically range from a minimum of 3°C (37°F) to a maximum of 28°C (82°F), with an average of 15°C (59°F). The month sees around 47 mm (1.9 in) of precipitation over approximately 9 days, accompanied by 82% humidity. In contrast, November brings cooler conditions, with temperatures dipping to a minimum of -2°C (28°F) and rising to a maximum of 16°C (61°F), averaging 8°C (47°F). November tends to be wetter, with 65 mm (2.6 in) of precipitation spread over about 11 days and higher humidity at 92%. For more details, check out this link: Southampton weather in November.

September and December present a stark contrast in weather conditions. In September, temperatures range from a mild 3°C (37°F) at night to a warm 28°C (82°F) during the day, with an average of 15°C (59°F). The month sees relatively low precipitation with 47 mm (1.9 in) across 9 days, making it a more comfortable time with humidity at 82%. In contrast, December cools down significantly, with minimum temperatures dropping to -3°C (27°F) and maximums reaching only 14°C (58°F), averaging 7°C (45°F). This month experiences increased precipitation, totaling 93 mm (3.7 in) over 13 days, and a higher humidity of 92%. The colder, wetter December weather creates a distinctly different atmosphere compared to the warmer, drier September. For more details on the December climate, check out Southampton weather in December.

Compare Southampton's Climate with Cities Worldwide

Conclusion: What to Expect From September Weather in Southampton

As summer gently fades, September in Southampton brings a delightful transition marked by milder temperatures and an invigorating freshness in the air. Unlike the sweltering heat of July and August, conditions are more temperate, with average highs inviting outdoor activities while cooler nights hint at the approaching autumn. Rainfall is somewhat moderate, occurring on a few days, yet the lush greenery it nurtures remains a hallmark of this time. With humidity levels around 82%, the air feels alive, creating a cozy, atmospheric charm that sets the scene for a beautiful autumn. For a more detailed look at weather patterns throughout the year, visit Southampton Climate.