September Weather in Koeln, Germany

Last updated: February 26, 2025

In September, Cologne, Germany, experiences a fascinating blend of weather conditions. With maximum temperatures reaching up to 34°C (93°F) and an average of 16°C (60°F), the month can feel quite warm, especially during the early days. However, as fall approaches, the minimum temperatures can dip to around 3°C (37°F), offering a stark contrast. The city also sees approximately 65 mm (2.5 in) of precipitation over 10 days, contributing to a relatively high humidity of 81%. This combination of warmth and moisture creates a dynamic and occasionally unpredictable climate, making September an intriguing time to explore Cologne’s vibrant atmosphere.

September Temperature in Koeln

In Koeln, Germany, September marks the transition from the sweltering summer heat to the crispness of autumn. With temperatures ranging from a minimum of 3°C (37°F) to a maximum of 34°C (93°F), this month showcases a delightful variety, featuring an average temperature of 16°C (60°F). As the warm days linger, the evenings grow cooler, hinting at the changing seasons ahead. This blend of warmth and coolness creates a unique charm, inviting both locals and visitors to enjoy outdoor activities while soaking in the vibrant fall colors that begin to emerge. Overall, September serves as a gentle reminder of summer’s fade while providing a comfortable backdrop for the month's festivities.

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

The chart illustrates September temperature patterns in Koeln, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends.
JanFebMarAprMayJunJulAugSepOctNovDec384145505766676760544541
Data source: Temperature data for Koeln 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 Koeln

In September, Koeln, Germany experiences a moderate precipitation of 65 mm (2.5 in) over approximately 10 days, marking a noticeable shift from the heavier rainfall seen in summer months like July and August. This reduction in both quantity and frequency of rain hints at the transition into autumn, where the weather gradually cools and becomes less tumultuous. Interestingly, while September’s totals are lower, they are still substantial compared to the drier spells of spring, indicating that even as the seasons change, Koeln remains comfortably wet. This month serves as a gentle reminder of the balance between summer's lushness and winter's embrace, paving the way for the more substantial rains that come in October and December.

September Precipitation Trends in Koeln

The chart displays monthly precipitation patterns in Koeln, 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.
JanFebMarAprMayJunJulAugSepOctNovDec9186913866609778659767127
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
Choose your preferred precipitation unit

September Humidity in Koeln

In September, Koeln experiences a noticeable shift in humidity, with levels averaging 81%. This marks a slight increase from the summer months, where humidity dipped to a comfortable 71% in August. As autumn approaches, the return to more humid conditions reflects a broader trend seen throughout the year, where Koeln's humidity typically peaks during the colder months. With an overarching average that fluctuates from a high of 92% in December to a low of 72% in July, September serves as a transitional month, signaling the onset of wetter weather as the city readies itself for the autumn chill.

September Average Humidity in Koeln

This chart illustrates the average monthly humidity levels in Koeln, 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%90%87%84%77%74%72%71%81%88%91%92%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Koeln

As summer winds down in Koeln, Germany, the UV Index in September drops to a moderate 5, requiring a burn time of about 30 minutes for unprotected skin. This marks a shift from the intense levels of 8 seen in June and July, where caution was paramount. While the summer months showcased a peak UV exposure with very high ratings, September maintains a balance, suggesting that while sun protection is still important, the risks have eased. This transitional month signifies a gradual return to lower UV levels as autumn approaches, with upcoming months presenting even milder exposures. For ongoing updates and insights into UV safety, be sure to check Koeln UV Index.

Maximum UV Index Levels in Koeln for September

The chart shows the monthly maximum UV Index (UVI) for Koeln 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.
JanFebMarAprMayJunJulAugSepOctNovDec124578875421
Data source: Koeln 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 Koeln

September in Köln, Germany, basks in a delightful 313 hours of sunshine, marking a transition from the vibrant summer months into the soft hues of autumn. As the sun gradually retreats from its July peak of 405 hours, September maintains a commendable brightness, outshining previous months like October and November. The month enjoys a notable diversity in daylight, providing a gentle blend of warmth and crispness that invites residents and visitors alike to explore the city’s beautiful parks and historic streets. This sunny embrace, while slightly diminished from the heights of May and June, still offers a radiant farewell to summer and a cheerful threshold to the cooler months ahead.

Monthly Sunshine Duration in Koeln: September Highlighted

The September sunshine duration represents the total number of hours Koeln 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.
JanFebMarAprMayJunJulAugSepOctNovDec113h202h267h336h387h383h405h377h313h232h183h129h
Data source: Koeln September Sunshine duration data generated using information from the Copernicus Climate Change Service.

Chance of Sun in Koeln During September

September in Koeln, Germany, unveils a moderate 36% chance of sunny weather, marking a subtle transition from the summer months. While this figure is slightly higher than the averages seen in June through August, it shows a notable decline compared to the spring months. As the year progresses from the sunnier days of summer, the likelihood of clear skies begins to wane, hinting at the approaching autumn. This makes September a delightful time for outdoor activities, as residents and visitors can still enjoy a decent chance of pleasant weather amidst the backdrop of the changing seasons.

Percentage of Sunny Days in September in Koeln

The chart illustrates the percentage of sunny days in Koeln 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 Koeln experiences clear skies throughout the year.
JanFebMarAprMayJunJulAugSepOctNovDec9%32%41%38%29%31%31%33%36%28%23%13%
Data source: Koeln September chance of sun data, generated using information from the Copernicus Climate Change Service.

Daylight Hours in Koeln in September

As summer transitions into autumn, September in Koeln, Germany, offers a delightful shift in daylight, with the sun gracing the city for 12 hours each day. This marks a gentle decline from the peak hours of sunlight experienced in June and July, where daylight reached a vibrant 16 and 15 hours respectively. The gradual tapering off continues through August, with 14 hours of sun, hinting at the cooler months ahead. September serves as a bridge, combining the warmth of late summer with the early whispers of fall, providing ample daylight for outdoor activities while subtly signaling the approach of shorter days in October and November. The trend clearly illustrates the ebb and flow of seasons, as Koeln basks in golden light before the days become shorter and the nights longer.

Average Daylight Hours in Koeln for September

The chart illustrates the variation in daylight duration in Koeln throughout the year, with September highlighted. It shows the monthly changes in daylight hours, calculated by summing the hours between sunrise and sunset.
JanFebMarAprMayJunJulAugSepOctNovDec8h 27m10h11h 55m13h 52m15h 34m16h 27m15h 59m14h 27m12h 34m10h 38m8h 53m7h 58m
Data source: Koeln daylight hours, calculated by summing the hours between sunrise and sunset for each day.

September Winds in Koeln

In Koeln, Germany, September heralds a notable shift in wind patterns as the average wind speed dips to 2.4 m/s (5 mph), marking the calmest month of the year. This gentle breeze contrasts sharply with the more vigorous winds characteristic of the spring and summer months, which see speeds ranging from 2.5 m/s to 3.9 m/s. As autumn approaches, the gradual decline in wind intensity suggests a transition to a more tranquil season, providing a serene backdrop for the changing foliage and cooler temperatures. This trend not only reflects a lull in the winds but also sets the stage for the brisk, refreshing breezes that will return in October, where average speeds pick back up to 3.8 m/s (8 mph), embracing the crispness of fall.

Average September Wind Speed in Koeln

The chart displays monthly wind speed patterns in Koeln, 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.
JanFebMarAprMayJunJulAugSepOctNovDec3.73.93.53.13.62.52.73.02.4 m/s3.82.83.5
Data source: Koeln September wind data, generated using information from the Copernicus Climate Change Service.

How September Weather in Koeln Compares to Other Months

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

September and January exhibit striking contrasts in weather patterns. In September, temperatures range from a mild 3°C (37°F) at night to a warm 34°C (93°F) during the day, with an average of 16°C (60°F). The month sees relatively lower precipitation at 65 mm (2.5 in) over about 10 days, and humidity levels sit at 81%. In contrast, January experiences much colder temperatures, with a minimum of -8°C (17°F) and a maximum of 15°C (59°F), averaging just 3°C (38°F). It also tends to be wetter, receiving 91 mm (3.6 in) of precipitation across 15 days, coupled with higher humidity at 91%. For more detailed insights on January weather, visit Koeln weather in January.

September and February present a stark contrast in weather conditions. September tends to be warmer, with minimum temperatures around 3°C (37°F) and maximums reaching up to 34°C (93°F), resulting in a pleasant average of 16°C (60°F). However, it also brings significant humidity at 81% and about 65 mm (2.5 in) of precipitation over approximately 10 days. In contrast, February is much colder, with temperatures dipping as low as -9°C (16°F) and averaging around 5°C (41°F), peaking at 20°C (68°F). This month also experiences higher precipitation levels at 86 mm (3.4 in), spread across about 13 days, accompanied by an even higher humidity of 90%. For more details about February weather in Koeln, you can visit Koeln weather in February.

September and March present contrasting weather patterns. In September, temperatures range from a mild 16°C (60°F) on average, peaking at a warm 34°C (93°F), with relatively high humidity at 81%. Despite a few rainy days, with a total precipitation of 65 mm (2.5 in), the month typically offers pleasant conditions. In contrast, March exhibits cooler temperatures, averaging only 7°C (45°F) and reaching a maximum of 22°C (72°F). It experiences more rainfall, totaling 91 mm (3.6 in) over about 15 days, and a higher humidity level of 87%. For more details on March weather, you can visit Koeln weather in March.

In comparing the weather between September and April, we observe notable differences in temperature and precipitation patterns. September tends to be much warmer, with average temperatures reaching 16°C (60°F) and a maximum of 34°C (93°F), while April experiences cooler conditions, with an average of just 10°C (51°F) and highs around 27°C (81°F). Additionally, September is slightly wetter, receiving 65 mm (2.5 in) of precipitation over about 10 days, compared to April's 38 mm (1.5 in) spread over 9 days. Humidity levels are also comparable, with September at 81% and April slightly higher at 84%. For more detailed insights on April weather, you can check Koeln weather in April.

In comparing September and May weather, both months exhibit mild temperatures and a fair amount of precipitation. September has a broader temperature range, with minimums reaching 3°C (37°F) and maximums soaring to 34°C (93°F), averaging around 16°C (60°F). In contrast, May typically starts with minimum temperatures of 0°C (33°F) and peaks at 33°C (91°F), with a lower average of 14°C (57°F). Precipitation is quite similar, with September experiencing around 65 mm (2.5 in) over approximately 10 days, while May sees slightly more at 66 mm (2.6 in) over 13 days. Humidity levels are also comparable, being slightly higher in September at 81% versus May's 77%. For more detailed insights on May weather, check out Koeln weather in May.

Comparing the weather in September and June reveals notable differences. In September, temperatures range from a chilly minimum of 3°C (37°F) to a warm maximum of 34°C (93°F), with an average of 16°C (60°F). The month sees approximately 65 mm (2.5 in) of precipitation over about 10 days, accompanied by a high humidity level of 81%. In contrast, June experiences milder temperatures, with a minimum of 8°C (46°F) and a maximum of 35°C (95°F), averaging around 19°C (67°F). Precipitation is slightly lower at 60 mm (2.4 in) across the same number of rainy days, but humidity remains lower at 74%. For more specific details on June weather, you can refer to this link: Koeln weather in June.

September and July exhibit quite distinct weather patterns. In September, temperatures range from a cool minimum of 3°C (37°F) to a warm maximum of 34°C (93°F), with an average temperature of 16°C (60°F). The month sees around 65 mm (2.5 in) of precipitation, spread over 10 days, and maintains a relatively high humidity level of 81%. In contrast, July offers warmer conditions, with temperatures ranging from a minimum of 8°C (48°F) to a scorching maximum of 40°C (104°F), and an average of 20°C (68°F). However, it experiences greater rainfall, accumulating about 97 mm (3.8 in) over 12 days, and slightly lower humidity at 72%. For a closer look at July weather specifics, you can visit Koeln weather in July.

In comparing the weather between September and August, September exhibits a broader temperature range with minimums dropping to 3°C (37°F) and maximums reaching up to 34°C (93°F). In contrast, August has higher averages, with minimum temperatures of 7°C (44°F) and maximums peaking at 37°C (99°F). While September experiences slightly less precipitation at 65 mm (2.5 in) across 10 days, August records a bit more with 78 mm (3.1 in) over 14 days. Additionally, September's humidity at 81% makes it feel more humid than August's 71%. For more detailed insights, you can refer to Koeln weather in August.

September and October present a noticeable shift in weather conditions. In September, temperatures range from a minimum of 3°C (37°F) to a maximum of 34°C (93°F), with an average temperature of 16°C (60°F). The month sees about 65 mm (2.5 in) of precipitation over 10 days, and humidity levels are around 81%. In contrast, October tends to be cooler, with temperatures dipping to a minimum of 1°C (34°F) and peaking at 27°C (80°F), averaging 12°C (54°F). Rainfall increases to 97 mm (3.8 in) across 15 days, accompanied by a rise in humidity to 88%. For more detailed insights into October's weather, you can visit Koeln weather in October.

September tends to showcase a wider temperature range, with minimums around 3°C (37°F) and highs reaching up to 34°C (93°F), making it a much warmer month on average at 16°C (60°F). In contrast, November is significantly cooler, featuring a minimum temperature of -4°C (26°F) and an average of just 7°C (45°F), with highs peaking at 20°C (68°F). Both months experience similar levels of precipitation, with September receiving about 65 mm (2.5 in) over approximately 10 days, while November sees a slightly higher 67 mm (2.6 in) across 13 days. Additionally, November brings increased humidity, averaging 91%, compared to September’s 81%. For more detailed information on November weather specifics, you can visit Koeln weather in November.

In September, the weather is significantly warmer, with temperatures ranging from a minimum of 3°C (37°F) to a maximum of 34°C (93°F), averaging around 16°C (60°F). The month sees about 65 mm (2.5 in) of precipitation over approximately 10 days and maintains a humidity level of 81%. In contrast, December brings much cooler temperatures, with the thermometer dipping as low as -5°C (24°F) and averaging 5°C (41°F), peaking at 15°C (59°F). Precipitation increases to 127 mm (5.0 in) spread over 20 days, while humidity rises to 92%. For a deeper look into December's weather conditions, visit Koeln weather in December.

Compare Koeln's Climate with Cities Worldwide

Conclusion: What to Expect From September Weather in Koeln

As September rolls into Köln, the weather begins to shift, offering a unique blend of warmth and coolness that sets it apart from the sweltering summer months. With maximum temperatures reaching 34°C while the average hovers around a mild 16°C, it’s an ideal time for outdoor activities. However, don’t forget your umbrella; September typically sees about 10 days of precipitation, adding a refreshing twist to the air’s natural 81% humidity. This transitional month beautifully juxtaposes the lingering warmth of summer with the crispness of fall, making it a delightful time to experience the city's vibrant atmosphere. For more details on seasonal trends, explore the Koeln Climate page.