Last updated: August 27, 2025
In September, Biel/Bienne, Switzerland, experiences a delightful transition from summer's warmth to the cooler embrace of autumn. The maximum temperature can reach a pleasant 29°C (84°F), while the average hovers around 15°C (59°F), providing comfortable days and chilly nights with a minimum of 1°C (34°F). Rainfall is a common companion, with 82 mm (3.2 in) of precipitation spread across 12 days, contributing to the region's lush landscapes. Humidity levels sit at a notable 81%, adding to the crisp freshness that defines this captivating month.
As September rolls into Biel/Bienne, Switzerland, the warm embrace of late summer gradually gives way to the crispness of fall. With minimum temperatures around 1°C (34°F), the city signals the onset of cooler days, while daytime averages reach a comfortable 15°C (59°F). The warmth peeks at a delightful 29°C (84°F), inviting locals and visitors alike to enjoy the stunning autumnal scenery before the chill deepens. This transition month offers a unique balance of lingering warmth and the refreshing bite of early autumn, creating a picturesque setting for outdoor adventures and cozy gatherings.
In September, Biel/Bienne experiences a transition into autumn with 82 mm (3.2 in) of precipitation over 12 days, marking a noticeable dip from the summer months of August and July, which recorded higher totals of 152 mm and 150 mm, respectively. This decrease in rainfall reflects the onset of cooler weather as the city begins to prepare for the fall season. Interestingly, September's totals are the lowest since April, highlighting a seasonal shift. Despite this reduction, the rainfall is still consistent enough to maintain the lush landscapes for which the region is known. As October approaches, the patterns indicate a gradual increase in precipitation, prepping the area for the wetter conditions characteristic of late fall.
In Biel/Bienne, Switzerland, September marks a transition as humidity settles at 81%, following the more comfortable 77% seen in August. This slight increase hints at the onset of autumn, where the air becomes crisper yet retains some warmth. Throughout the year, Biel/Bienne experiences peak humidity in the winter months with levels reaching 91% in January and December. As spring unfolds into summer, humidity typically decreases, bottoming out in August. However, as September arrives, it signals a subtle return to higher humidity levels, aligned with the wetter climate of fall. Overall, the trend reflects the region's characteristic seasonal changes, where autumn's embrace brings a gradual rise back towards the winter's moist air.
In September, Biel/Bienne experiences a UV Index of 6, categorizing the sun's intensity as high with a burn time of 25 minutes for unprotected skin. This marks a noticeable drop from the peak summer months, where values soared to 9, but still warrants caution, especially for outdoor activities during midday. As autumn approaches, the UV levels gradually decrease, transitioning from the very high exposure experienced in July and August. Observing these trends can help residents and visitors alike enjoy the vibrant fall days while protecting their skin from harmful UV rays. For more detailed information, visit Biel/Bienne UV Index.
UV Risk Categories
September in Biel/Bienne, Switzerland, brings a welcoming embrace of sunshine, with 329 hours of bright light illuminating the picturesque landscapes. This month marks a subtle transition as the days begin to shorten, following a vibrant summer peak in July with 418 hours of sunshine. While August experiences a slight decline in sunlight to 388 hours, September continues to offer a generous amount of golden hours, although noticeably less than the summer months. As the year progresses into autumn, the sunshine begins to wane, but September remains a delightful moment of warmth, setting the stage for the rich colors of fall. The gradual descent in daylight from this point onward adds a reflective charm to the beauty of Biel/Bienne, making it a captivating time to enjoy the outdoors before the chill of winter arrives.
In September, Biel/Bienne, Switzerland, enjoys a 39% chance of sunny weather, marking a slight uptick from the summer months. This fall month sees a blend of lingering summer warmth and the onset of autumn, offering residents and visitors alike a refreshing respite. Although September's sunshine likelihood is less than the earlier summer peak, it still stands favorably compared to the following months. As the weather cools down, there's a balance between vibrant days and the increasing clouds of October, making September a lovely time for outdoor activities before the chill sets in.
As summer gives way to autumn in Biel/Bienne, September marks a noticeable shift in daylight duration, with the sun shining for approximately 12 hours each day. This brief decline follows the peak of summer, where daylight persisted for a delightful 15 hours in both June and July. As days gradually shorten, the vibrant energy of summer transitions into the cozy ambiance of fall, leading to 14 hours of daylight in August. This gradual decrease prepares the region for the even shorter days of October and November, highlighting a rhythmic pattern of light that reflects the changing seasons and invites the community to embrace the beauty of autumn.
As September arrives in Biel/Bienne, Switzerland, the gentle whispers of wind begin to calm, with an average speed of just 1.7 m/s (4 mph). This marks a noticeable drop from the earlier summer months, where breezes are typically more lively. Throughout the year, wind speeds have gradually fluctuated, peaking in late spring at 2.8 m/s (6 mph) in May, before tapering off as autumn approaches. The transition into September reflects this trend of softening winds, creating a serene atmosphere that invites leisurely strolls along the scenic lakeside. As the cozy embrace of fall sets in, the soothing ambiance of September suggests a delightful pause, allowing residents and visitors alike to savor the beauty of the changing seasons.
Weather in Biel/Bienne varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Biel/Bienne, focusing on differences in temperature, rainfall, humidity, and UV levels.
September and January present stark contrasts in weather. September features a milder temperature range, with a minimum of 1°C (34°F) and an average of 15°C (59°F), peaking at a comfortable 29°C (84°F). This month also sees 82 mm (3.2 in) of precipitation over approximately 12 days, coupled with a moderate humidity of 81%. In contrast, January experiences much colder conditions, with temperatures dropping to a minimum of -14°C (8°F), an average of just 1°C (33°F), and a maximum of 15°C (59°F). The precipitation increases slightly to 98 mm (3.9 in) over 13 days, alongside higher humidity levels at 91%. For a detailed look at the weather specifics, you can check Biel/Bienne weather in January.
In September, the weather is generally warmer, with temperatures ranging from a minimum of 1°C (34°F) to a maximum of 29°C (84°F) and an average of 15°C (59°F). The month sees about 82 mm (3.2 in) of precipitation over approximately 12 days, accompanied by humidity levels around 81%. In contrast, February experiences much colder temperatures, with a minimum of -13°C (8°F) and a maximum of 17°C (64°F), averaging just 3°C (38°F). This month has slightly higher precipitation at 84 mm (3.3 in) over the same number of days, but with a higher humidity of 89%. For a deeper understanding of winter conditions, you can check out Biel/Bienne weather in February.
In comparing the weather of September and March, we see notable differences in temperature and precipitation patterns. September typically enjoys milder temperatures, ranging from a minimum of 1°C (34°F) to a maximum of 29°C (84°F), with an average around 15°C (59°F). The month experiences a fair amount of rain, with 82 mm (3.2 in) over about 12 days and a humidity level of 81%. In contrast, March is significantly colder, with temperatures ranging from a low of -13°C (9°F) to a high of 21°C (69°F) and an average of only 5°C (42°F). It is also wetter, with 100 mm (3.9 in) of precipitation spread across 16 days and higher humidity at 87%. For a detailed overview, you can check out Biel/Bienne weather in March.
September and April present distinct contrasts in weather. In September, temperatures range from a minimum of 1°C (34°F) to a maximum of 29°C (84°F), with an average of 15°C (59°F). This month experiences around 82 mm (3.2 in) of precipitation over 12 days, accompanied by humidity levels of 81%. In contrast, April typically has cooler temperatures, with a minimum of -5°C (23°F) and a maximum of 25°C (77°F), averaging 9°C (49°F). Precipitation is lower at 67 mm (2.6 in) across 11 days and humidity is slightly higher at 84%. For a more detailed look at weather patterns, you can check Biel/Bienne weather in April.
September and May present distinct weather characteristics despite having similar maximum temperatures. In September, temperatures range from a chilly 1°C (34°F) to a warm 29°C (84°F), with an average of 15°C (59°F), while May begins with slightly cooler temperatures, peaking at 29°C (85°F) but having an average of only 13°C (55°F). Additionally, September experiences 82 mm (3.2 in) of precipitation over 12 days, whereas May sees a higher rainfall total of 156 mm (6.1 in) across 18 days, indicating a wetter environment. Humidity levels are relatively close in both months, with September at 81% and May at 80%. For more detailed insights, check out Biel/Bienne weather in May.
In comparing the weather between September and June, September tends to have cooler temperatures, with minimums dropping to 1°C (34°F) and an average of 15°C (59°F), while June has warmer conditions, featuring a minimum of 5°C (41°F) and an average of 18°C (64°F). Rainfall is also more abundant in June, with a total of 141 mm (5.6 in) over 17 days compared to September's 82 mm (3.2 in) over 12 days. Despite both months having a similar humidity level, September enjoys slightly lower humidity at 81%, while June stands at 82%. For a closer look at June’s weather specifics, check out Biel/Bienne weather in June.
September's weather features a broader temperature range, with minimums dipping to 1°C (34°F) and maximums reaching up to 29°C (84°F), offering a moderate average of 15°C (59°F). In comparison, July tends to be warmer, with minimum temperatures around 8°C (46°F) and maximums soaring to 35°C (95°F), resulting in a higher average of 19°C (67°F). Additionally, July experiences more precipitation, totaling 150 mm (5.9 in) over 15 days, while September accounts for 82 mm (3.2 in) over 12 days. Both months maintain high humidity levels, with September at 81% and July slightly higher at 82%. For more insights on July weather, visit Biel/Bienne weather in July.
In comparing the weather of September and August, it's clear that September experiences cooler temperatures, with a minimum of 1°C (34°F) and an average of 15°C (59°F), compared to August's minimum of 6°C (44°F) and average of 19°C (66°F). In terms of maximum temperatures, August reaches higher peaks, averaging 33°C (92°F) compared to September's maximum of 29°C (84°F). Additionally, September sees more moderate precipitation at 82 mm (3.2 in) over 12 days, while August is wetter, with 152 mm (6.0 in) spread over 16 days. Despite the reduction in rain, September is slightly more humid at 81% compared to August's 77%. For more detailed insights on August weather, you can visit Biel/Bienne weather in August.
September and October present a noticeable shift in weather conditions. In September, temperatures range from a minimum of 1°C (34°F) to a maximum of 29°C (84°F), resulting in a pleasant average of 15°C (59°F). The month sees a total precipitation of 82 mm (3.2 in) over 12 days, with humidity levels at 81%.
Conversely, October brings cooler temperatures, with a minimum of -2°C (29°F) and an average of 10°C (50°F), peaking at 23°C (73°F). Rainfall increases slightly to 104 mm (4.1 in) over 13 days, accompanied by a rise in humidity to 89%. For more detailed insights about weather patterns in October, visit Biel/Bienne weather in October.
September and November exhibit distinct differences in weather patterns. September boasts a wider temperature range, with daytime highs reaching up to 29°C (84°F), while average temperatures hover around a pleasant 15°C (59°F). In contrast, November experiences markedly cooler conditions, with average temperatures plummeting to just 4°C (40°F), and nighttime lows potentially dropping to -4°C (25°F). Both months see similar levels of precipitation, with September totaling 82 mm (3.2 in) over 12 days and November slightly higher at 84 mm (3.3 in) over 13 days. Moreover, humidity tends to be higher in November at 89%, compared to 81% in September. For more details on November conditions, you can check Biel/Bienne weather in November.
September and December present contrasting weather patterns. In September, temperatures are more moderate, ranging from a minimum of 1°C (34°F) to a maximum of 29°C (84°F), with an average of around 15°C (59°F). The month sees 82 mm (3.2 in) of precipitation over 12 days and maintains a relatively high humidity of 81%. In contrast, December brings significantly colder temperatures, with a minimum of -8°C (18°F), an average of 2°C (36°F), and a maximum of 13°C (56°F). This month experiences more precipitation, totaling 138 mm (5.4 in) across 19 days, along with a slight increase in humidity to 91%. For a detailed view of the December climate, check this link: Biel/Bienne weather in December.
As September rolls into Biel/Bienne, it marks a transition from the warmth of summer to the crispness of autumn. The temperatures begin to cool, offering a pleasant average that invites outdoor exploration, while the occasional rain—spreading across about twelve days—adds a refreshing backdrop to the changing scenery. This month sees a noticeable rise in humidity, contributing to the rich, vibrant colors of the landscape as nature prepares for the cooler months ahead. For a deeper understanding of how September weather fits into the overall climate pattern, you can explore more about Biel/Bienne's unique climate Biel/Bienne Climate.