Last updated: February 26, 2025
Bonn, Germany, experiences a diverse September climate characterized by a maximum temperature reaching 34°C (93°F), while the average hovers around a crisp 16°C (60°F). Minimum temperatures can drop to a cool 2°C (36°F), making this month a transition into the fall season. Rainfall is noted with a total of 55 mm (2.2 in) across approximately 10 days, contributing to an humidity level of around 81%. Overall, September in Bonn offers a mix of warm days and refreshing cooler nights, perfect for enjoying the changing landscapes.
In September, Bonn experiences a delightful transition from the height of summer into the crispness of autumn. Temperatures range from a minimum of 2°C (36°F) to a pleasantly warm maximum of 34°C (93°F), offering a summer-like warmth during the day while cooler evenings hint at the changing season. The average temperature settles at a comfortable 16°C (60°F), making this month an ideal time for outdoor activities and enjoying the city's beautiful parks. As daylight begins to dwindle, the slight chill at night serves as a reminder that fall is just around the corner, inviting visitors and locals alike to embrace the rich tapestry of autumn colors starting to unfold. Overall, September in Bonn strikes a harmonious balance between lingering summer vibes and the onset of autumn's refreshing embrace.
In September, Bonn experiences a modest decline in precipitation, receiving about 55 mm (2.2 in) of rain over 10 days. This amount is slightly lower than the summer months, reflecting a transition into autumn. Compared to the wetter July and August, which saw 93 mm (3.7 in) and 80 mm (3.2 in) respectively, September’s drier spell signals a shift in weather patterns. As the days grow shorter and temperatures cool, residents can expect sporadic showers, creating a refreshing ambiance perfect for enjoying the changing foliage. This month’s precipitation marks a notable contrast to the heavier rainfall typical of December, which often totals around 100 mm (4.0 in), showcasing the region's dynamic climate throughout the year.
In Bonn, Germany, September experiences a noticeable shift in humidity, with levels hovering around 81%. This is a significant drop from the peak summer months, where July and August average 72% and 71%, respectively, reflecting the drier climate of summer. As autumn approaches, the humidity begins to rise again, aligning more closely with the colder months ahead. Interestingly, the trend shows a gradual increase from the low of June and July, where humidity reached its annual minimum, hinting at the return of moisture as the year transitions. This fluctuation illustrates the typical climatic rhythm of Bonn, where seasonal changes dictate the air's moisture content, paving the way for the wetter conditions typical in October and beyond.
In September, Bonn experiences a moderate UV Index of 5, indicating a continued transition from the summer's peak sun exposure. This level of UV radiation means that spending time outdoors requires some precaution, with a burn time of approximately 30 minutes for unprotected skin. Following the very high indices of July and August, which boasted UV Index levels of 8, September serves as a reminder that while the intensity decreases, vigilance is still necessary. As the year shifts into autumn, the UV Index begins to decline, marking a notable trend where sun safety remains important but the urgency lessens. For more detailed insights, check out Bonn UV Index.
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September in Bonn, Germany, shines brightly with 314 hours of sunshine, a delightful transition from the sun-drenched summer months. As the year progresses, the sunshine hours steadily rise, peaking in July with 407 hours. However, as autumn beckons, the hours begin to dwindle, dropping significantly to 232 hours by October. This nuanced balance between the exuberance of summer and the cozy embrace of fall creates a captivating atmosphere, inviting residents and visitors alike to relish the fading warmth of the season before the clouds settle in for winter.
In Bonn, Germany, the chance of sunny weather in September hovers around 38%, reflecting a gradual increase as the summer months wane. This figure is notably higher than the mid-year months of June, July, and August, each averaging around 31%, but slightly lower than the fluctuating peaks of spring, where March reached 42%. As the year transitions from the warmth of summer to the crispness of autumn, September offers a refreshing blend of sunny spells, making it an attractive time for outdoor activities before the cloudier months set in. Overall, while not an outright guarantee of sunshine, September in Bonn certainly holds its ground as a charming month for those seeking to bask in the last rays of summer.
As September unfolds in Bonn, Germany, daylight begins to wane, marking a subtle transition from the vibrant summer months. With an average of 12 hours of sunlight, September offers a gentle decline from August's 14 hours, signaling the onset of autumn. This month stands out as a bridge between the long, sun-drenched days of summer—when daylight peaks at 16 hours in June—and the shorter, more subdued days of fall, where daylight dips to 10 hours by October. The gradual reduction in daylight not only invites cooler temperatures but also paints the landscape with the rich hues of autumn, encouraging residents to savor the remaining warmth of the season.
As summer fades into autumn, September in Bonn, Germany, greets residents with a gentle breeze, featuring an average wind speed of 2.2 m/s (5 mph)—the calmest of the year. This month’s subtle winds mark a notable shift from the slightly stronger gusts of the preceding summer, where average speeds hovered around 2.6 to 2.9 m/s (6 mph). The overall trend reveals a gradual decline in wind speed through the warmer months, reaching this seasonal low in September before picking up again in October with speeds bouncing back to 3.7 m/s (8 mph). This seasonal ebb and flow captures Bonn's transition from the lively days of summer into the more tranquil aura of fall, inviting both residents and visitors to savor the crispness of the changing season.
The weather in Bonn 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 Bonn and find detailed weather information for every month.
In September, temperatures range significantly from a cool 2°C (36°F) at night to a warm 34°C (93°F) during the day, with an average of 16°C (60°F). The month experiences about 55 mm (2.2 in) of precipitation over approximately 10 days and maintains a humidity level of 81%. In contrast, January brings much colder conditions, with temperatures dipping to a minimum of -8°C (18°F) and peaking at only 14°C (58°F), averaging around 3°C (38°F). This month has higher precipitation at 72 mm (2.8 in) across about 14 days, and humidity rises to 91%. For more detailed information, you can check Bonn weather in January.
September and February present stark contrasts in weather conditions. In September, temperatures can range from a cool 2°C (36°F) at night to a warm 34°C (93°F) during the day, with an average of 16°C (60°F). The month experiences about 55 mm (2.2 in) of precipitation over approximately 10 days, along with a humidity level of 81%. In contrast, February is notably colder, with temperatures dropping to a minimum of -10°C (14°F) and reaching a maximum of 21°C (69°F), averaging around 5°C (41°F). This month sees higher precipitation at 68 mm (2.7 in) over 12 days and increased humidity at 90%. For more details, check out Bonn weather in February.
When comparing the weather in September and March, significant differences are evident. September boasts a much warmer climate, with temperatures ranging from a minimum of 2°C (36°F) to a maximum of 34°C (93°F) and an average of 16°C (60°F). In contrast, March presents a cooler atmosphere, with temperatures dipping as low as -10°C (15°F) and averaging around 7°C (45°F). Precipitation is also noteworthy; September experiences about 55 mm (2.2 in) over 10 days, while March sees more rainfall at 72 mm (2.8 in) across 15 days. Additionally, humidity levels are slightly higher in March at 87%, compared to September's 81%. For more details, check out Bonn weather in March.
When comparing the weather in September and April, we see notable differences in temperature and precipitation. September experiences a wider temperature range, with minimums of 2°C (36°F) and maximums reaching up to 34°C (93°F), while April's temperatures are generally cooler, starting at a minimum of -3°C (26°F) and peaking at 27°C (81°F). September also tends to be slightly wetter, with 55 mm (2.2 in) of rainfall over about 10 days, whereas April registers 36 mm (1.4 in) of precipitation across 9 days. Humidity levels are fairly similar, with September at 81% and April at 84%. For more details, check out the comprehensive overview of Bonn weather in April.
September and May exhibit notable differences in weather patterns. September typically enjoys a wider temperature range, with minimums around 2°C and maximums reaching up to 34°C, while May's temperatures are slightly cooler, with minimums at 0°C and maximums hitting 33°C. Precipitation is a bit higher in May, averaging 70 mm over 13 days compared to September's 55 mm over 10 days. Additionally, humidity levels are slightly elevated in September at 81%, compared to May's 77%. For more detailed information on May's weather, you can check Bonn weather in May.
September and June present distinct weather patterns characterized by temperature variations and humidity levels. September experiences a broader temperature range, with minimums dropping to 2°C (36°F) and maximums reaching up to 34°C (93°F), while the average temperature settles around 16°C (60°F). In contrast, June showcases a milder climate, with minimum temperatures starting at 8°C (47°F) and highs peaking at 35°C (95°F), averaging around 19°C (66°F).
While both months see a fair amount of precipitation, with June receiving slightly more at 68 mm (2.7 in) over 11 days compared to September's 55 mm (2.2 in) over 10 days, the humidity levels differ as well. September's humidity is higher at 81%, compared to June's 74%. For more detailed information about June weather, check out Bonn weather in June.
When comparing the weather in September and July, it’s clear that July experiences warmer temperatures with a minimum of 8°C (47°F) and an average of 20°C (67°F), while September sees lower temperatures, dropping to a minimum of 2°C (36°F) and an average of 16°C (60°F). July's maximum temperature can reach a sizzling 40°C (105°F), compared to September's high of 34°C (93°F). In terms of precipitation, July is also wetter, with 93 mm (3.7 in) over 11 days, compared to September's 55 mm (2.2 in) across 10 days. Moreover, September tends to be more humid, averaging 81%, whereas July has a relatively lower humidity level of 72%. For more detailed information, check out Bonn weather in July.
When comparing the weather in September to that of August, it's clear that September experiences cooler temperatures, with a minimum of 2°C and an average of 16°C, whereas August maintains a warmer minimum of 7°C and an average of 20°C. Additionally, September sees a maximum temperature of 34°C, slightly lower than August's peak of 36°C. Precipitation is also noteworthy; September has 55 mm of rain over 10 days compared to August's 80 mm over 15 days, indicating that September is not only drier but also less humid at 81%, compared to August's 71% humidity. For a deeper look into August weather specifics, visit Bonn weather in August.
September and October exhibit notable differences in weather patterns. In September, temperatures range from a minimum of 2°C (36°F) to a maximum of 34°C (93°F), with an average of 16°C (60°F). This month experiences 55 mm (2.2 inches) of precipitation over approximately 10 days, accompanied by a humidity level of 81%.
In contrast, October sees cooler temperatures, with a minimum of 0°C (33°F) and a maximum of 27°C (80°F), averaging around 12°C (54°F). October is wetter, recording 71 mm (2.8 inches) of precipitation over about 14 days and an increased humidity of 88%. For a more detailed look at the weather specifics, check out Bonn weather in October.
September and November present contrasting weather patterns, highlighting the transition from late summer to autumn. In September, temperatures range from a mild 2°C (36°F) at night to a scorching 34°C (93°F) during the day, with an average of 16°C (60°F). The month sees relatively lower humidity at 81% and about 55 mm (2.2 in) of precipitation over 10 days. In contrast, November experiences chillier conditions, with temperatures dipping to a minimum of -4°C (26°F) and peaking at 20°C (69°F), averaging 7°C (45°F). This month also has slightly higher humidity at 91% and similar precipitation levels of 54 mm (2.1 in) over 12 days. For more detailed information, check out Bonn weather in November.
September and December showcase markedly different weather conditions. In September, temperatures range from a cool minimum of 2°C (36°F) to a warm maximum of 34°C (93°F), with an average of 16°C (60°F). There’s moderate rainfall of 55 mm (2.2 in) over about 10 days, with humidity levels around 81%. In contrast, December brings the chill, with temperatures dipping significantly, ranging from -5°C (23°F) to a maximum of 15°C (59°F) and averaging only 5°C (41°F). The month is wetter as well, with precipitation reaching 100 mm (4.0 in) over 19 days and an increased humidity of 92%. For a more detailed look at the December climate, check out Bonn weather in December.
As September rolls in, Bonn experiences a striking transition from the warm embrace of summer to the cooler caress of autumn. With temperatures fluctuating widely, this month offers both pleasant days and crisp nights, making it uniquely dynamic compared to the more stable weather patterns of July and August. The chance of rain increases, though the overall amount remains moderate, adding a refreshing touch to the air. Moreover, the higher humidity levels contribute to a somewhat muggy feel, especially on warmer days. This blend of warmth and moisture not only enhances the city's lush scenery but also invites residents and visitors alike to embrace the changing seasons. For a deeper dive into what to expect throughout the year, check out the full details on Bonn Climate.