September Weather in Knebworth, United Kingdom

Last updated: March 17, 2025

In September, Knebworth, United Kingdom, experiences a delightful transition into autumn, with maximum temperatures soaring to a warm 28°C (83°F) while the average settles around a comfortable 15°C (59°F). Nights can be quite cool, dipping to a minimum of 3°C (38°F), reminding residents of the season's shift. Amidst the variable weather, precipitation is a common occurrence, totaling 49 mm (1.9 in) over about 10 days, contributing to the region's lush greenery. With an 82% humidity level, the air feels rich and refreshing, encapsulating the essence of early autumn in this charming town.

September Temperature in Knebworth

As September unfolds in Knebworth, the transition from summer to autumn becomes evident with temperatures that start to cool down. The month typically features minimums around 3°C (38°F) and reaches an average of 15°C (59°F), peaking at a comfortable 28°C (83°F) during the warmest days. This pleasant blend of warmth echoes the tail end of summer while hinting at the upcoming chill. Compared to the scorching highs of July and August, where temperatures soared past 30°C (86°F), September provides a refreshing reprieve, making it an ideal time for enjoying the outdoors without the oppressive heat. As autumn sets in, the crispness in the air serves as a gentle reminder that change is just around the corner.

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

The chart illustrates September temperature patterns in Knebworth, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends.
JanFebMarAprMayJunJulAugSepOctNovDec404345495561656459534643
Data source: Temperature data for Knebworth 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 Knebworth

In September, Knebworth experiences a total precipitation of 49 mm (1.9 in), marking a decrease from the summer months yet maintaining the trend of moderate rainfall typical for this time of year. With rainfall occurring on 10 days, September offers a balance between wet and dry days, allowing for those crisp early autumn afternoons. Compared to the preceding months, where precipitation peaked in June (74 mm) and August (72 mm), September’s totals are more subdued, hinting at a gradual transition towards the wetter autumn season. This shift sets the stage for October's higher averages, where total precipitation jumps to 86 mm (3.4 in), suggesting that Knebworth is preparing for the more dramatic weather changes that autumn typically brings.

September Precipitation Trends in Knebworth

The chart displays monthly precipitation patterns in Knebworth, 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.
JanFebMarAprMayJunJulAugSepOctNovDec545156326574677249865183
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Knebworth

As summer gives way to autumn in Knebworth, United Kingdom, September experiences a notable increase in humidity, reaching 82%. This marks a slight uptick from the drier months of July and August, where humidity levels dipped to 71% and 76%, respectively. The gradual rise in September signals the onset of the wetter season, as the air becomes more saturated with moisture in preparation for the cooler months ahead. Notably, following September, the humidity levels soar, peaking in the winter months of January and February at a staggering 91% and 89%. This trend highlights Knebworth's characteristic seasonal shifts, where a humid September is a precursor to the lush, moist environment that defines the chilly end of the year.

September Average Humidity in Knebworth

This chart illustrates the average monthly humidity levels in Knebworth, 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 Knebworth

As September unfolds in Knebworth, the UV Index settles at 6, categorizing the exposure as high with a burn time of just 25 minutes. This marks a slight decline from the very high levels seen in the peak summer months of July and August, where indices reached 8. The transition into autumn brings a more moderate sun, yet residents should remain vigilant as the sun's rays can still cause damage. Compared to earlier months, such as January or February, where the UV Index hovers around 1 or 2, September's levels remind us that sun protection is crucial even as we welcome the cooler days. For more detailed information on Knebworth's UV patterns, explore Knebworth UV Index.

Maximum UV Index Levels in Knebworth for September

The chart shows the monthly maximum UV Index (UVI) for Knebworth 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.
JanFebMarAprMayJunJulAugSepOctNovDec124578876421
Data source: Knebworth 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 Knebworth

As summer gracefully fades into autumn, September in Knebworth, United Kingdom, shines with an impressive 300 hours of sunshine, making it a delightful transition month. This figure marks a notable decline from the sun-drenched peak of July, which boasts 404 hours, yet maintains a vibrant charm compared to the gloomier winter months ahead. With sunny days tailing off from the height of summer, September offers a splendid opportunity to relish the last warm rays before the crisp chill of October, which sees a drop to 241 hours. This pattern reflects a gradual dimming of daylight, yet Knebworth remains bathed in a warm glow, inviting locals and visitors alike to soak in the beauty of early autumn before the shorter days set in.

Monthly Sunshine Duration in Knebworth: September Highlighted

The September sunshine duration represents the total number of hours Knebworth 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.
JanFebMarAprMayJunJulAugSepOctNovDec98h148h210h319h398h389h404h368h300h241h144h109h
Data source: Knebworth September Sunshine duration data generated using information from the Copernicus Climate Change Service.

Chance of Sun in Knebworth During September

As September rolls into Knebworth, the likelihood of basking in sunny weather reaches 29%, a modest yet promising chance that hints at the transition from summer to autumn. This percentage shows a slight uptick compared to the sunniest months of April and July, though it falls short of the peak summer days. The trend reveals a gradual variance in sunshine probability throughout the year, with the sunniest months giving way to cooler, cloudier days ahead. While September may not boast the brightest days, it still offers a fair opportunity to enjoy some late-season sunshine before the winter chill sets in. So, whether you're planning a leisurely stroll or an outdoor gathering, keep an eye on the skies, as September still holds the charm of sunny surprises.

Percentage of Sunny Days in September in Knebworth

The chart illustrates the percentage of sunny days in Knebworth 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 Knebworth experiences clear skies throughout the year.
JanFebMarAprMayJunJulAugSepOctNovDec20%25%28%48%31%27%38%24%29%24%32%16%
Data source: Knebworth September chance of sun data, generated using information from the Copernicus Climate Change Service.

Daylight Hours in Knebworth in September

As autumn approaches, September in Knebworth, United Kingdom, greets its residents with a transition in daylight, offering about 12 hours of sunlight. This reduction follows the long, bright days of summer where daylight peaked at 16 hours in June and July, creating a vibrant atmosphere for outdoor activities. As the days grow shorter, following the gradual descent from 15 hours in May to 14 hours in August, September marks a gentle decline that sets the stage for the impending crispness of fall. This month encapsulates a balance, with enough daylight to enjoy the fading warmth while signaling the inevitable retreat into the shorter days of October and November.

Average Daylight Hours in Knebworth for September

The chart illustrates the variation in daylight duration in Knebworth throughout the year, with September highlighted. It shows the monthly changes in daylight hours, calculated by summing the hours between sunrise and sunset.
JanFebMarAprMayJunJulAugSepOctNovDec8h 22m9h 57m11h 55m13h 54m15h 39m16h 34m16h 4m14h 30m12h 35m10h 36m8h 49m7h 52m
Data source: Knebworth daylight hours, calculated by summing the hours between sunrise and sunset for each day.

September Winds in Knebworth

As September rolls into Knebworth, the breeze begins to mellow, with average wind speeds cooling to 3.4 m/s (8 mph). This gentle shift is in line with the trend observed throughout the summer months, where wind speeds hovered around similar figures. Compared to the slightly more robust winds of late spring and early summer, September’s breezes offer a tranquil atmosphere perfect for leisurely walks and outdoor gatherings. Notably, as we transition into October, expectations rise for a resurgence in wind speeds, mirroring the striking uptick seen in previous years. Thus, September stands as a serene interlude, letting the local landscape bask in a soft, inviting wind before the more invigorating gusts of autumn arrive.

Average September Wind Speed in Knebworth

The chart displays monthly wind speed patterns in Knebworth, 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.
JanFebMarAprMayJunJulAugSepOctNovDec4.44.94.63.54.33.33.44.03.4 m/s4.64.14.6
Data source: Knebworth September wind data, generated using information from the Copernicus Climate Change Service.

How September Weather in Knebworth Compares to Other Months

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

September and January present contrasting weather patterns. In September, temperatures range from a mild 3°C (38°F) at night to a warm 28°C (83°F) during the day, with an average of 15°C (59°F). The month experiences 49 mm (1.9 in) of precipitation over 10 days, accompanied by a moderate humidity of 82%. In stark contrast, January is much colder, with temperatures dipping as low as -5°C (24°F) at night and peaking at 14°C (58°F) during the day, averaging just 5°C (41°F). Precipitation slightly increases to 54 mm (2.1 in) over the same number of days, but the humidity rises to 91%, lending a chill to the air. For more details on January weather, you can check Knebworth weather in January.

September and February present quite contrasting weather conditions. In September, temperatures range from a mild 3°C (38°F) at night to a warm 28°C (83°F) during the day, averaging around 15°C (59°F). The month sees 49 mm (1.9 in) of rainfall over about 10 days, with humidity levels averaging 82%. In contrast, February experiences much chillier temperatures, with nighttime lows dropping to -6°C (22°F) and daytime highs reaching only 18°C (65°F), yielding an average of just 6°C (43°F). Precipitation in February is slightly higher at 51 mm (2.0 in), occurring over 11 days, while humidity levels rise to 89%. For more detailed information on February weather, you can visit Knebworth weather in February.

September and March present contrasting weather patterns. In September, temperatures range from a cooler minimum of 3°C (38°F) to a warm average of 15°C (59°F), peaking at 28°C (83°F). During this month, precipitation averages 49 mm (1.9 in) over about 10 days, with humidity at 82%. In contrast, March experiences lower temperatures with a minimum of -6°C (22°F) and an average of 7°C (45°F), reaching a maximum of 22°C (71°F). Precipitation is slightly higher at 56 mm (2.2 in) and occurs on approximately 13 days, coupled with a higher humidity of 86%. For more detailed information, you can check Knebworth weather in March.

When comparing the weather in September and April, one can observe distinct differences in temperature and humidity. September typically enjoys moderate temperatures, ranging from a minimum of 3°C (38°F) to a maximum of 28°C (83°F), with an average of 15°C (59°F). In contrast, April presents cooler conditions, with temperatures dipping as low as -2°C (29°F) and averaging 9°C (49°F), although it can still reach up to 27°C (80°F) on warmer days. Precipitation is slightly higher in September at 49 mm (1.9 in) over about 10 days, compared to April's 32 mm (1.3 in) across 8 days. Humidity levels are fairly consistent, with September showing 82% and April slightly higher at 85%. For a more detailed look at the weather conditions, you can visit Knebworth weather in April.

When comparing the weather in September and May, several differences emerge. September tends to be slightly warmer, with average temperatures reaching 15°C (59°F) compared to May's average of 13°C (55°F). The maximum temperatures in September can reach up to 28°C (83°F), while May's high is a bit lower at 26°C (79°F). However, May experiences more precipitation, totaling 65 mm (2.5 in) over 11 days, compared to September's 49 mm (1.9 in) over 10 days. Humidity levels are relatively similar, with September at 82% and May at 79%. For more detailed information about the weather in May, you can check this link: Knebworth weather in May.

When comparing the weather in September and June, we see notable differences in temperature and precipitation. In September, temperatures range from a chilly minimum of 3°C (38°F) to a pleasant maximum of 28°C (83°F), with an average of 15°C (59°F). The month also experiences relatively high humidity at 82% and receives about 49 mm (1.9 inches) of rain over 10 rainy days. In contrast, June boasts warmer temperatures, with a minimum of 7°C (45°F), an average of 16°C (62°F), and a maximum of 31°C (88°F). Although June has slightly higher precipitation at 74 mm (2.9 inches) over the same 10 days, its humidity is slightly lower at 80%. For a detailed look at June weather, visit Knebworth weather in June.

In comparing the weather between September and July, we see notable differences in temperature and precipitation. September experiences a wider temperature range, with minimums of 3°C (38°F) and maximums reaching 28°C (83°F), averaging at 15°C (59°F). In contrast, July is warmer, with minimum temperatures of 9°C (48°F) and maximums soaring to 36°C (96°F), averaging 18°C (65°F). Rainfall is more prevalent in July, totaling 67 mm (2.6 in) over 12 days, compared to September's 49 mm (1.9 in) across 10 days. Humidity levels are also higher in September at 82%, while July boasts a more comfortable 71%. For more details, you can check Knebworth weather in July.

In comparing the weather of September to August, September typically experiences cooler temperatures, with a minimum of 3°C (38°F) and an average of 15°C (59°F), contrasting with August’s minimum of 8°C (47°F) and average of 18°C (64°F). The maximum temperatures in September reach 28°C (83°F) compared to August's hotter peak of 34°C (93°F). Additionally, September sees increased precipitation, averaging 49 mm (1.9 in) over 10 days, while August has heavier rainfall of 72 mm (2.8 in) over 13 days. Humidity is slightly higher in September at 82%, compared to 76% in August. For a more detailed look at August weather patterns, check out Knebworth weather in August.

September boasts warmer temperatures, with a minimum of 3°C and an average of 15°C, reaching as high as 28°C. However, it experiences less rainfall and slightly lower humidity, with 49 mm of precipitation over 10 days. In contrast, October brings cooler weather, starting with a minimum temperature of 1°C and an average of 12°C, while the maximum reaches 23°C. This month is also wetter, recording 86 mm of precipitation over 12 days and a higher humidity level of 90%. For more details, you can check the Knebworth weather in October.

September typically boasts a warmer climate than November, with average temperatures ranging from a minimum of 3°C (38°F) to a maximum of 28°C (83°F), leading to a comfortable average of 15°C (59°F). In contrast, November sees lower temperatures, with a minimum of -2°C (29°F) and a maximum of 16°C (62°F), resulting in a cooler average of 8°C (46°F). While both months experience similar levels of precipitation—about 49 mm (1.9 in) in September and 51 mm (2.0 in) in November—November's higher humidity at 92% compared to September's 82% can make it feel even chillier. For a more detailed overview of November conditions, you can check Knebworth weather in November.

In September, temperatures range from a chilly 3°C (38°F) at night to a warm 28°C (83°F) during the day, with an average of 15°C (59°F). The month sees moderate precipitation of 49 mm (1.9 in) over about 10 days and a humidity level of 82%. In contrast, December experiences a cooler climate with temperatures dropping to a minimum of -5°C (23°F) and an average of 6°C (43°F), peaking at 14°C (58°F). The precipitation increases to 83 mm (3.3 in) spread over 14 days, accompanied by higher humidity at 92%. For more detailed insights on winter conditions, check Knebworth weather in December.

Compare Knebworth's Climate with Cities Worldwide

Conclusion: What to Expect From September Weather in Knebworth

As September rolls in, Knebworth experiences a notable transition in its weather. The days can be warm, occasionally reaching 28°C, but a cool breeze reminds us that autumn is on the horizon. With an average temperature of 15°C, the month offers a comfortable balance, yet it can dip to a brisk 3°C at night. Rainfall is more frequent this time, with nearly a third of the month seeing precipitation. The high humidity level adds to the overall feeling of the season, creating a unique atmosphere compared to the drier, warmer summer months. For a detailed understanding of how the weather shapes life in Knebworth, check out Knebworth Climate.