September Weather in Bellevue, Switzerland

Last updated: August 27, 2025

In Bellevue, Switzerland, September brings a pleasant transition into autumn, characterized by an average temperature of 15°C (59°F), with maximum highs reaching 28°C (82°F) and minimum lows dipping to 3°C (38°F). This month experiences approximately 74 mm (2.9 in) of rainfall spread over 10 days, leading to a humidity level of 81%, which adds a fresh feel to the crisp October air. Whether you are exploring the charming streets or enjoying the breathtaking scenery, September offers a delightful blend of comfortable warmth and refreshing moisture, making it an ideal time to visit this picturesque locale.

September Temperature in Bellevue

In September, Bellevue, Switzerland experiences a delightful transition from the sweltering summer months to the cooler days of autumn. With minimum temperatures around 3°C (38°F) and a pleasant average of 15°C (59°F), the city invites visitors to enjoy the crisp air and stunning landscapes. The maximum temperature peaks comfortably at 28°C (82°F), offering plenty of opportunities for outdoor activities amidst the turning leaves. As the month progresses, the warmth begins to fade, setting the stage for cooler October days, but September's mild climate remains ideal for exploring Bellevue’s charming scenery and vibrant culture.

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

The chart illustrates September temperature patterns in Bellevue, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Bellevue, September typically has an average temperature of {2}°C ({3}°F), with highs reaching up to {4}°C ({5}°F) and lows dropping to around {6}°C ({7}°F).
JanFebMarAprMayJunJulAugSepOctNovDec343943495564676659514236
Data source: Temperature data for Bellevue 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 Bellevue

In September, Bellevue, Switzerland experiences a moderate rainfall of 74 mm (2.9 in), with precipitation occurring on 10 days throughout the month. This marks a noticeable decline from the heavier downpours of summer, particularly May, which sees its peak at 172 mm (6.8 in). As the region transitions into autumn, September's precipitation is much lighter than the preceding months, yet it prepares the landscape for the wetter months ahead. As autumn approaches, the decrease in both total rainfall and number of rainy days hints at the end of the more humid summer season, setting the stage for the upcoming months where precipitation amounts significantly increase.

September Precipitation Trends in Bellevue

The chart displays monthly precipitation patterns in Bellevue, 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. In Bellevue, September typically receives around {2} mm ({3} inches) of precipitation spread over approximately {4} days.
JanFebMarAprMayJunJulAugSepOctNovDec116961346717212111010875116109203
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Bellevue

As summer transitions to autumn in Bellevue, Switzerland, September brings a refreshing yet moderate humidity level of 81%. This slight increase from August's 77% reflects the gradual return of moisture to the air as the days grow shorter and cooler. Following the warm months, where humidity generally hovered around 82%, September's levels prepare the landscape for the wetter conditions typical of autumn. As the year progresses, October and November see humidity rise again to 89%, mirroring the winter months that follow, where the humidity reaches a peak of 91%. This cyclical pattern of humidity not only shapes the local climate but also contributes to the lush, verdant beauty that Bellevue is renowned for during these transitional months.

September Average Humidity in Bellevue

This chart illustrates the average monthly humidity levels in Bellevue, with September’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In September, average humidity in Bellevue is approximately {2}%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec91%89%87%84%80%82%82%77%81%89%89%91%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Bellevue

As September arrives in Bellevue, Switzerland, the UV Index reflects a high exposure category, registering at 7, which is slightly lower than the peak of summer months. This indicates that while it’s still a good time to enjoy outdoor activities, sun protection remains essential, as even a short burn time of 25 minutes can lead to skin damage. The trend this month is a gradual tapering from the intense UV levels of July and August, which peaked at 9 and 8, respectively, both categorized as very high. As temperatures begin to cool, remember to stay vigilant with sun safety practices. For more detailed information, check out the Bellevue UV Index.

Maximum UV Index Levels in Bellevue for September

The chart shows the monthly maximum UV Index (UVI) for Bellevue 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. In September, the maximum UV index in Bellevue typically reaches {2}, which falls under the {3} exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec2367810987532
Data source: Bellevue 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 Bellevue

In September, Bellevue experiences a gratifying transition as the summer sun begins to wane, offering an impressive 327 hours of sunshine. This marks a slight decrease from the radiant heights of July and August, which boasted 414 and 384 hours respectively, but still ensures a warm and inviting atmosphere for outdoor activities. The trend showcases Bellevue's enviable position in the light spectrum, with the sunny days of summer lingering just a little longer into the fall. As the autumn leaves start to dance, nature's vibrant colors complement the golden rays, making September an ideal time for exploration and relaxation in this picturesque Swiss locale.

Monthly Sunshine Duration in Bellevue: September Highlighted

The September sunshine duration represents the total number of hours Bellevue 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.
JanFebMarAprMayJunJulAugSepOctNovDec159h226h292h351h352h394h414h384h327h281h219h186h
Data source: Bellevue September Sunshine duration data generated using information from the Copernicus Climate Change Service.

Chance of Sun in Bellevue During September

In September, Bellevue, Switzerland maintains a 40% chance of sunny weather, which reflects a trend of variability in the region's climate as summer transitions to autumn. This month marks a slight decrease from the more sun-kissed August, which enjoys a 46% chance of sunshine. Interestingly, the sunshine probability in September closely aligns with October's forecast of 43%, suggesting a gradual shift towards the cloudier months ahead. Overall, while sunny days are certainly possible, travelers should remain prepared for the whimsical weather that September can bring, balancing sunlit moments with the fresh embrace of early autumn.

Percentage of Sunny Days in September in Bellevue

The chart illustrates the percentage of sunny days in Bellevue 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 Bellevue experiences clear skies throughout the year.
JanFebMarAprMayJunJulAugSepOctNovDec20%38%51%53%30%37%40%46%40%43%36%37%
Data source: Bellevue September chance of sun data, generated using information from the Copernicus Climate Change Service.

Daylight Hours in Bellevue in September

As September arrives in Bellevue, Switzerland, the days begin to shorten, with daylight lasting approximately 12 hours. This marks a gentle transition from the vibrant summer months of July and August, which boast up to 15 hours of sunlight, providing ample time for outdoor activities. Following the bountiful light of late spring and summer, September's daylight still offers a satisfying balance, dipping gradually towards the shorter days of autumn. This subtle decrease in daylight is part of a predictable trend, as months like October and November soon follow with only 10 and 9 hours of daylight respectively, signaling the onset of winter's embrace.

Average Daylight Hours in Bellevue for September

The chart illustrates the variation in daylight duration in Bellevue throughout the year, with September highlighted. It shows the monthly changes in daylight hours, calculated by summing the hours between sunrise and sunset.
JanFebMarAprMayJunJulAugSepOctNovDec9h 4m10h 20m11h 56m13h 34m14h 58m15h 41m15h 18m14h 4m12h 29m10h 52m9h 25m8h 40m
Data source: Bellevue daylight hours, calculated by summing the hours between sunrise and sunset for each day.

September Winds in Bellevue

As September unfolds in Bellevue, Switzerland, the gentle breezes bring a noticeable dip in average wind speed, falling to 1.4 m/s (3 mph), the lowest of the year. This tranquil shift contrasts with the more lively winds of spring and early summer, where speeds peaked at 2.2 m/s in April. The calmness of September invites a serene ambiance, perfect for leisurely strolls along the lakeside, as the cozy autumn vibes settle in. Following the warm summer months, which maintained a consistent 1.7 m/s, September's delicate whispers of wind hint at the approaching change of season, fostering an atmosphere of reflection amidst the enchanting landscape.

Average September Wind Speed in Bellevue

The chart displays monthly wind speed patterns in Bellevue, 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.
JanFebMarAprMayJunJulAugSepOctNovDec1.91.82.02.21.91.61.71.71.4 m/s1.81.71.8
Data source: Bellevue September wind data, generated using information from the Copernicus Climate Change Service.

How September Weather in Bellevue Compares to Other Months

Weather in Bellevue varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Bellevue, focusing on differences in temperature, rainfall, humidity, and UV levels.

September and January exhibit stark contrasts in weather patterns. In September, temperatures range from a mild 3°C (38°F) to a warm 28°C (82°F), with an average of 15°C (59°F). This month experiences relatively moderate precipitation at 74 mm (2.9 in) over about 10 days, and humidity levels hover around 81%. In contrast, January brings much colder conditions, with temperatures ranging from a frigid -13°C (8°F) to a maximum of 14°C (58°F) and an average of just 1°C (34°F). Precipitation increases to 116 mm (4.6 in) over 11 days, and humidity rises slightly to 91%. For more details, check out Bellevue weather in January.

September and February present contrasting weather patterns. In September, temperatures range from a cool 3°C (38°F) at night to a warm 28°C (82°F) during the day, with an average of 15°C (59°F). Despite relatively mild conditions, September experiences around 74 mm (2.9 in) of precipitation over approximately 10 days, coupled with a humidity level of 81%. In stark contrast, February is much colder, with minimum temperatures dropping to -12°C (10°F) and an average of only 4°C (39°F). The maximum temperatures reach up to 17°C (64°F), but the month is marked by increased precipitation at 96 mm (3.8 in) over 11 days and higher humidity at 89%. For a more detailed look at February weather, visit Bellevue weather in February.

In comparing the weather between September and March, we observe significant differences in temperature and precipitation. September enjoys milder conditions with average temperatures around 15°C (59°F), while March is much colder, with average temperatures only reaching 6°C (43°F). The maximum temperature in September can soar to 28°C (82°F), compared to a maximum of 21°C (69°F) in March. Additionally, March experiences more precipitation, totaling 134 mm (5.3 in) over 14 days, while September has 74 mm (2.9 in) across 10 days. The humidity levels are relatively high in both months, with March slightly higher at 87% compared to September's 81%. For more detailed information on March conditions, you can check Bellevue weather in March.

September and April present distinct weather patterns, reflecting the transition from summer to autumn and the onset of spring, respectively. In September, temperatures range from a minimum of 3°C (38°F) to a maximum of 28°C (82°F), with an average of 15°C (59°F). The month typically sees about 74 mm (2.9 in) of precipitation over approximately 10 days, alongside a humidity level of 81%. In contrast, April experiences cooler weather, with temperatures ranging from a low of -6°C (21°F) to a high of 25°C (77°F) and an average temperature of 10°C (49°F). This month records slightly less precipitation at 67 mm (2.6 in) over roughly 9 days, with humidity just slightly higher at 84%. For more information on the weather patterns during this time, you can check Bellevue weather in April.

When comparing the weather in September and May, some intriguing differences emerge. September boasts a milder average temperature of 15°C (59°F), with highs reaching up to 28°C (82°F), while May has an average of 13°C (55°F), peaking at 29°C (84°F). However, May experiences significantly more precipitation, totaling 172 mm (6.8 in) over 16 days, compared to September's 74 mm (2.9 in) across 10 days. The humidity levels are relatively similar, with September at 81% and May slightly lower at 80%. For more detailed information, you can check Bellevue weather in May.

When comparing the weather between September and June, we see notable differences in temperature and precipitation. September experiences a temperature range from a minimum of 3°C (38°F) to a maximum of 28°C (82°F), with an average of 15°C (59°F). In contrast, June offers warmer conditions, with temperatures ranging from 6°C (42°F) to 33°C (92°F) and an average of 18°C (64°F). Additionally, June has higher precipitation, totaling 121 mm (4.8 in) over 14 days, compared to September's 74 mm (2.9 in) over 10 days. Despite the slight increase in precipitation in June, humidity remains fairly consistent between the two months, with September at 81% and June at 82%. For more detailed insights, you can check Bellevue weather in June.

September weather is typically milder compared to July, with average temperatures ranging from a minimum of 3°C (38°F) to a maximum of 28°C (82°F), while July boasts higher averages, with minimums around 9°C (48°F) and maximums reaching up to 34°C (93°F). Additionally, July experiences greater precipitation, averaging 110 mm (4.3 in) over 13 days, compared to September's 74 mm (2.9 in) over 10 days. Humidity levels remain similar in both months, around 81% in September and 82% in July. For more detailed insights, you can check the Bellevue weather in July.

In comparing the weather between September and August, September presents a cooler climate with temperatures ranging from a minimum of 3°C to a maximum of 28°C, averaging around 15°C. In contrast, August features warmer temperatures, with a minimum of 8°C, an average of 19°C, and a peak of 33°C. While September experiences slightly less precipitation (74 mm over 10 days) compared to August's 108 mm over 13 days, its humidity is marginally higher at 81%. For more detailed information on August weather, you can refer to Bellevue weather in August.

September and October exhibit a notable transition in weather patterns, reflecting the shift from late summer to early autumn. In September, temperatures range from a mild 3°C (38°F) at night to a warm average of 15°C (59°F) during the day, peaking at 28°C (82°F). This month experiences 74 mm (2.9 in) of precipitation over about 10 days, with humidity at 81%. Conversely, October brings a cooler climate, with minimum temperatures dropping to -1°C (31°F) and an average of 10°C (51°F), reaching a maximum of 22°C (72°F). Precipitation increases to 116 mm (4.6 in) spread across 11 days, while humidity rises to 89%. For more details on October weather, you can check Bellevue weather in October.

September typically enjoys warmer temperatures with a minimum of 3°C (38°F) and an average high of 28°C (82°F), making it a pleasant month for outdoor activities. However, it also sees a fair amount of rain, averaging 74 mm (2.9 in) over about 10 days, and humidity levels are relatively high at 81%.

In contrast, November brings a stark shift in weather, with a lower average temperature that ranges from a minimum of -3°C (27°F) to a maximum of 19°C (66°F) and an overall average of just 5°C (42°F). The month is typically wetter, with 109 mm (4.3 in) of precipitation spread over about 13 days, and humidity rises to 89%. For those interested in more details, you can check Bellevue weather in November.

September and December present a stark contrast in weather patterns. In September, temperatures range from a pleasant 3°C (38°F) at night to a warm 28°C (82°F) during the day, accompanied by moderate precipitation of 74 mm (2.9 in) over about 10 days, leading to a relative humidity of 81%. In contrast, December experiences much colder conditions, with temperatures dipping as low as -9°C (16°F) and reaching a maximum of only 13°C (56°F). Precipitation increases significantly to 203 mm (8.0 in) over 18 days, coupled with higher humidity at 91%. For more detailed insights, you can explore Bellevue weather in December.

Compare Bellevue's Climate with Cities Worldwide

Conclusion: What to Expect From September Weather in Bellevue

As September settles over Bellevue, the transition from summer to autumn becomes evident, with notable shifts in temperature and weather patterns. The warm days, peaking at 28°C (82°F), create a pleasant atmosphere, but the average temperature cools to 15°C (59°F), offering a refreshing reprieve from the summer heat. Expect increased rainfall, with 74 mm (2.9 in) accumulating over 10 days, adding an invigorating freshness to the air, while the humidity lingers at a notable 81%. This blend of warm days and crisp nights sets September apart from the drier, hotter months that precede it, inviting both locals and visitors to embrace the changing season. For a deeper dive into Bellevue's unique weather patterns, explore Bellevue Climate.