Last updated: August 27, 2025
September in St. Moritz, Switzerland brings a captivating blend of crisp mountain air and vibrant fall foliage. With temperatures ranging from a brisk -12°C (11°F) at night to a pleasant 18°C (65°F) during the day, the average settles around 6°C (44°F), making it an ideal time for outdoor adventures. The month sees 15 days of precipitation, accumulating to 126 mm (5.0 in), contributing to the lush landscapes that characterize this season. Humidity remains high at 83%, enhancing the refreshing atmosphere of this stunning Alpine resort. Embrace the beauty of early autumn with its cool breezes and scenic views as St. Moritz transforms into a picturesque getaway.
September in St. Moritz, Switzerland marks a distinct transition as summer gently fades into autumn. With minimum temperatures dipping to around -12°C (11°F) and an average of 6°C (44°F), the chill becomes more pronounced compared to the balmy warmth of August. Daytime highs can reach a comfortable 18°C (65°F), providing a brief reprieve before winter's grasp tightens. This month showcases a notable shift from the previous summer's peak, as the landscapes begin to don their autumn hues, combining crisp air with stunning mountain vistas. As the leaves change and the air cools, September invites visitors to relish in the serene beauty of St. Moritz, balancing between the lingering warmth of summer and the impending chill of winter.
In September, St. Moritz experiences a notable shift in precipitation, accumulating 126 mm (5.0 in) of rain over 15 days. This marks a slight decrease from the summer months, particularly August, which typically sees the highest rainfall of the year at 195 mm (7.7 in) across 21 days. As autumn settles in, the rainfall in September reflects a transition towards drier conditions, with precipitation levels decreasing compared to the abundant summer downpours. The month serves as a bridge from the lush greenery of summer to the crisp, cooler days of October, which brings around 148 mm (5.8 in) of rain in just 11 days. The patterns indicate that while September remains relatively wet, the overall trend points towards a gradual decline in precipitation as St. Moritz heads deeper into the autumn season.
In September, St. Moritz experiences a humidity level of 83%, marking a slight increase from the drier summer months of July and August, where humidity dipped to 83% and 80% respectively. As the region transitions into autumn, the air retains a hint of summer's warmth while moisture levels begin to rise again, foreshadowing the wet conditions of October, which sees humidity jump back up to 90%. This trend of increasing humidity from late summer to early autumn is characteristic of the area, as it prepares for the snowy months ahead, when humidity will peak again alongside the chill in the air during December.
As summer fades into early autumn, St. Moritz experiences a noticeable shift in its UV Index, marking September as a transitional month with an index of 7—a high exposure category. This signals a decrease from the peak values seen during July and August, where the index reached 10, but still necessitates caution with a burn time of just 25 minutes. With the high UV ratings persisting into September, it's essential for outdoor enthusiasts to remain vigilant while enjoying the stunning alpine scenery. As the UV levels drop in October, reaching a 6, visitors can still enjoy the beautiful landscapes but should keep the importance of sun safety in mind. For detailed trends and safety tips, visit St. Moritz UV Index.
UV Risk Categories
As summer transitions into autumn, September in St. Moritz experiences a delightful shift, showcasing 309 hours of sunshine. This month marks a gentle decline from the dazzling heights of 410 hours in July, yet it remains vibrant compared to the earlier months of the year. The sunshine hours gradually taper off as winter approaches, following a peak in June with 386 hours. Notably, September's rays evoke a picturesque backdrop for outdoor activities and leisurely strolls, capturing the essence of change in this stunning Swiss resort. As nature prepares for winter's embrace, the lingering warmth of September sunlight invites visitors to savor every moment before the shorter days of October set in.
In September, the likelihood of sunny weather in St. Moritz, Switzerland, drops to 26%, marking a subtle decline from the peak summer months. The sunniest days are prominent in the winter months with February and March boasting 37% and 40% chances respectively. However, as the seasons transition towards autumn, sunshine becomes less predictable, paralleling a general trend seen throughout the year. Following the summer's moderate sunshine, September’s figures reflect a gradual shift, hinting at the approaching cooler weather, yet still offering moments of brightness against the breathtaking backdrop of the Alps. This month serves as a gentle reminder to embrace the fleeting warmth before the crisp autumn air fully takes over.
As summer transitions into autumn in St. Moritz, Switzerland, September offers a picturesque blend of daylight and cool, crisp air. With approximately 12 hours of sunlight, the days gradually shorten, marking a gentle shift from the 15 hours experienced in the peak of summer. This decrease in daylight continues the trend observed throughout the year, where January's dark chill with only 9 hours of light transforms into brighter spring and summer months before heading back into the cozy embrace of early winter. The dynamic interplay of daylight highlights not only the natural beauty of the region but also invites visitors to enjoy the breathtaking scenery while it still basks in the glow of substantial sunlight.
As summer transitions into autumn, September in St. Moritz, Switzerland, brings a gentle sigh of wind at an average speed of 1.2 m/s (3 mph). This marks one of the year's calmer periods, slightly quieter than the breezes of August. The winds have been relatively consistent throughout the year, oscillating between mild speeds, with a peak of 1.7 m/s (4 mph) during the lush months of late spring and summer. As the golden hues of autumn begin to envelop the alpine landscape, the softer winds of September create a serene backdrop, inviting visitors to enjoy the stunning scenery in a peaceful atmosphere while hinting at the brisker gusts that will accompany the arrival of fall.
Weather in St. Moritz varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in St. Moritz, focusing on differences in temperature, rainfall, humidity, and UV levels.
September and January exhibit stark contrasts in weather conditions. September features a milder temperature range, with minima of -12°C (11°F) and maxima reaching 18°C (65°F), accompanied by an average of 6°C (44°F). It is also characterized by higher humidity at 83% and significant precipitation of 126 mm (5.0 in) over 15 days. In contrast, January is much colder, with temperatures plummeting to a minimum of -27°C (-17°F) and a maximum of only 2°C (36°F), resulting in an average temperature of -11°C (12°F). Precipitation in January is lower at 75 mm (2.9 in) over 10 days, but the humidity rises to 92%. For more detailed weather information, check St. Moritz weather in January.
In comparing the weather between September and February, September offers a milder climate with an average temperature of 6°C (44°F), ranging from a low of -12°C (11°F) to a comfortable high of 18°C (65°F). This month sees 126 mm (5.0 in) of precipitation spread over about 15 days, accompanied by a relatively high humidity level of 83%. In contrast, February presents a much colder scenario, with an average temperature of -8°C (18°F) that dips to a chilling low of -28°C (-18°F) and a maximum of only 6°C (43°F). Precipitation in February is lower, at 59 mm (2.3 in) across 11 days, but humidity rises slightly to 89%. Overall, February is far colder and drier than September. For more detailed weather conditions, you can check St. Moritz weather in February.
In comparing the weather of September and March, notable differences in temperature and conditions can be observed. September features a milder range with temperatures reaching a minimum of -12°C (11°F) and an average of 6°C (44°F), peaking at 18°C (65°F). It also experiences more precipitation, totaling 126 mm (5.0 in) over 15 days, coupled with a humidity level of 83%. In contrast, March is markedly colder, with temperatures dropping to a minimum of -26°C (-14°F) and averaging -5°C (23°F), surging only to a maximum of 11°C (52°F). The month sees less precipitation, measuring 90 mm (3.5 in) across 13 days, and a slightly higher humidity of 87%. These contrasting weather patterns highlight the transition from the tail end of summer to the lingering chill of late winter. For a detailed look at March conditions, you can check St. Moritz weather in March.
When comparing the weather in September and April, it’s clear that both months present unique characteristics. September generally has a milder climate, with average temperatures ranging from -12°C (11°F) to a maximum of 18°C (65°F), while April tends to be colder with temperatures varying from -19°C (-1°F) to a maximum of 12°C (54°F). September receives more precipitation, totaling 126 mm (5.0 in) over approximately 15 days, compared to April's 99 mm (3.9 in) across 12 days. Additionally, while humidity is quite similar in both months at around 83% and 84% respectively, September's weather offers a more gradual transition into autumn warmth, as opposed to April's lingering chill of winter. For a detailed look at the weather in April, you can refer to St. Moritz weather in April.
When comparing the weather in September and May, both months exhibit similar maximum temperatures, reaching up to 18°C (65°F). However, September enjoys a slightly milder average temperature of 6°C (44°F) compared to May's average of 3°C (38°F). Rainfall is more prevalent in May, with total precipitation of 150 mm (5.9 in) occurring over 22 days, in contrast to September's 126 mm (5.0 in) over 15 days. Additionally, humidity levels are relatively high in both months, with September at 83% and May at 80%. For a more detailed look at May weather in St. Moritz, you can check out St. Moritz weather in May.
When comparing the weather in September and June, we find notable differences in temperature and precipitation. September's temperatures range from a chilly minimum of -12°C (11°F) to a pleasant maximum of 18°C (65°F), with an average of 6°C (44°F). In contrast, June offers milder conditions, with temperatures swinging from a minimum of -2°C (28°F) to a maximum of 25°C (77°F) and an average of 9°C (49°F). Precipitation is also slightly higher in June at 159 mm (6.3 in) over 19 days, compared to September's 126 mm (5.0 in) spread over 15 days. Humidity levels are comparable, with September at 83% and June at 82%. For a closer look at June weather patterns specifically, you can check St. Moritz weather in June.
In comparing the weather of September and July, notable differences emerge. September experiences cooler temperatures, with a minimum of -12°C (11°F), averaging around 6°C (44°F) and peaking at 18°C (65°F). In contrast, July offers more warmth, with minimum temperatures at 0°C (33°F), an average of 10°C (51°F), and maximums reaching 23°C (73°F). While both months exhibit high humidity at 83%, July sees slightly more precipitation at 159 mm (6.3 in) over 21 days compared to September's 126 mm (5.0 in) over 15 days. For more detailed insights, you can check St. Moritz weather in July.
In comparing the weather between September and August, September features significantly cooler temperatures, with a minimum of -12°C (11°F) and an average of 6°C (44°F), while August showcases milder conditions, with temperatures ranging from a minimum of 0°C (33°F) to a maximum of 21°C (70°F). Additionally, September experiences less precipitation overall, accumulating 126 mm (5.0 in) over 15 days, compared to August's heavier rainfall of 195 mm (7.7 in) across 21 days. Humidity levels are relatively similar, with September at 83% and August slightly lower at 80%. For a detailed look at the weather conditions in August, you can visit St. Moritz weather in August.
In September, St. Moritz experiences a mild transition into autumn with temperatures ranging from a minimum of -12°C (11°F) to a maximum of 18°C (65°F) and an average of 6°C (44°F). The month sees a total precipitation of 126 mm (5.0 in) over 15 days, coupled with a relatively high humidity of 83%.
Conversely, October brings cooler temperatures, with a minimum of -10°C (14°F) and a maximum of 14°C (57°F), resulting in an average temperature dropping to 2°C (36°F). Rainfall increases slightly to 148 mm (5.8 in) across 11 days, and humidity rises to 90%.
This shift highlights the more pronounced chill and dampness of October in contrast to the milder, albeit still variable, September weather. For more details, you can check St. Moritz weather in October.
In September, temperatures in St. Moritz range from a minimum of -12°C (11°F) to a maximum of 18°C (65°F), with an average temperature of 6°C (44°F). The month experiences approximately 126 mm (5.0 in) of precipitation over 15 days, accompanied by a humidity level of 83%.
Conversely, November brings a significant drop in temperatures, with minima dipping to -22°C (-8°F) and a maximum of just 8°C (47°F), resulting in an average temperature of -4°C (25°F). The precipitation slightly increases to 132 mm (5.2 in) over 14 days, and humidity rises to 88%. These contrasting weather patterns highlight a transition from the relatively mild conditions of September to the much colder and wetter climate of November. For more details, check out St. Moritz weather in November.
September and December present stark contrasts in weather. In September, temperatures range from a chilly min of -12°C (11°F) to a mild max of 18°C (65°F), with an average of 6°C (44°F). The month sees about 126 mm (5.0 in) of precipitation over 15 days, accompanied by a humidity level of 83%.
In contrast, December brings a significant drop in temperature, with a minimum of -26°C (-14°F), an average of -9°C (16°F), and a maximum of only 2°C (37°F). Despite a similar precipitation total of 125 mm (4.9 in) over 15 days, the humidity rises slightly to 90%. For more details on winter conditions, see St. Moritz weather in December.
As September unfolds in St. Moritz, the weather presents a striking transition from the warmth of summer to the crispness of autumn. With temperatures averaging around 6°C (44°F), the cool mornings and evenings invite cozy attire, making it a perfect time for outdoor activities like hiking amidst the fall foliage. Unlike the summer months, precipitation becomes more common, with about 15 rainy days contributing to a higher humidity level of 83%. This blend of cool temperatures and increased moisture creates a serene and invigorating atmosphere, setting the stage for the enchanting beauty of the Alpine landscape. For a deeper understanding of what to expect throughout the year, explore the full details in St. Moritz Climate.