Last updated: August 27, 2025
In September, Sierre, Switzerland experiences a delightful transition into autumn, with temperatures ranging from a minimum of -5°C (23°F) to a maximum of 22°C (72°F). The average temperature hovers around a pleasant 9°C (49°F), creating a crisp atmosphere that invigorates the senses. This month also brings an average precipitation amount of 90 mm (3.6 in) over approximately 12 days, contributing to the lush landscapes that define the region. With humidity levels around 81%, visitors can expect a charming blend of cool breezes and refreshing rain, perfect for exploring the scenic beauty of Sierre during this enchanting time of year.
As September rolls into Sierre, Switzerland, temperatures begin to show a notable transition from the warmth of summer to the cool embrace of autumn. With minimum temperatures dipping to a brisk -5°C (23°F) and daytime highs reaching a comfortable 22°C (72°F), the month offers a delightful range of average temperatures around 9°C (49°F). This shift marks a significant change from the preceding months, when summer highs frequently touched 28°C (82°F). Considering that July and August bask in the warmth with average temperatures of 14°C (57°F) and 13°C (56°F) respectively, September presents a refreshing reprieve that hints at the cooler days to come, while still enjoying the lingering mildness of late summer. The changing temperatures encourage both locals and visitors to relish the stunning autumn landscapes that begin to unfold as the days grow shorter.
In September, Sierre, Switzerland experiences a moderate dip in precipitation, with the month accumulating 90 mm (3.6 in) of rainfall over approximately 12 days. This marks a noticeable decline from the wetter months of May and June, which recorded 160 mm (6.3 in) and 130 mm (5.1 in) respectively. As the region transitions into autumn, the precipitation pattern becomes less intense, but still supports the lush landscapes that Switzerland is known for. This gradual shift hints at the impending winter, as October climbs back up to 135 mm (5.3 in), reflecting a seasonal rhythm that balances rainfall and the vibrant colors of fall foliage.
As summer gives way to autumn in Sierre, Switzerland, September experiences a slight uptick in humidity, rising to 81% after the driest month of August. This seasonal shift is accompanied by a gradual increase in moisture levels, reminiscent of the more humid spring months. The overall trend indicates that while humidity is at its lowest in late summer, it begins to climb, peaking again in the colder months of late autumn and winter, where levels hover around 89%. This cycle reflects the region's characteristic transitions, where even as temperatures drop, the air retains a noticeable moisture, hinting at the approaching winter chill.
As summer transitions into autumn, Sierre, Switzerland, experiences a notable shift in its UV Index, with September recording a UV Index of 7, indicating a high exposure category. This reflects a decrease from the intense UV levels of July and August, which peaked at 10 and 9 respectively. In September, the recommended burn time extends to 25 minutes, allowing for more leisurely outdoor activities while still emphasizing the importance of sun protection. Notably, the trend illustrates a gradual decline in UV exposure as the year progresses, moving toward the cooler months. For more detailed information, check the Sierre UV Index.
UV Risk Categories
As September unfolds in Sierre, Switzerland, it offers a delightful conclusion to the summer, basking in 323 hours of sunshine. This month sees a slight dip from the peak summer months of July and August, which boasted 416 and 383 hours respectively, yet it still retains a vibrant glow. In comparison to the earlier part of the year, where hours of sunlight steadily increased from 176 hours in January to a seasonal high in July, September serves as a gentle transition into the more subdued autumn months. As daylight gradually wanes, with October bringing 288 hours and November dipping further to 232 hours, September stands out as a significant reminder of the sun-drenched pleasures of summer before the cooler days set in.
In Sierre, Switzerland, September experiences a 33% chance of sunny weather, reflecting a slight dip compared to the summer months. This gradual decline follows the peak sunshine chances of July (35%) and August (37%), indicating that the warmth of summer is beginning to wane. Interestingly, September's likelihood of sun remains on par with November and exceeds that of earlier months like April (44%) and May (32%). As autumn approaches, the weather can still offer pleasant, sunny days, making it a favorable time for outdoor activities amidst the changing foliage. Overall, while September may not guarantee abundant sunshine, it still holds a reasonable chance for those seeking to enjoy the last glimpses of summer warmth before the chill of October sets in.
As summer gracefully fades into autumn in Sierre, Switzerland, the daylight hours begin to wane in September, offering a serene midpoint with 12 hours of daylight. This month serves as a gentle transition from the peak of summer's 15 hours in June and July, while still providing a generous amount of light compared to the impending darker months of October and November. The gradual decline in daylight, from the vibrant 14 hours in August to the softer hues of September, marks a significant shift as nature prepares for the cooler seasons. This rhythmic ebb and flow of daylight not only enhances the beauty of Sierre's landscapes but also invites residents and visitors alike to savor the increasingly crisp autumn air as they bask in the waning glow of the sun.
As September unfurls in Sierre, Switzerland, the gentle caress of the wind brings a subtle transition into autumn. With an average wind speed of 1.0 m/s (2 mph), the breezes remain soft and soothing, a continuation of the calm that defined the summer months. This slight drop from previous months highlights a trend toward more tranquil days as the year slowly approaches its close. Unlike the more brisk winds of January and February, which reach up to 1.6 m/s (4 mph), September's delicate whispers invite leisurely strolls and cozy gatherings. As the beautiful fall colors emerge, the gentle winds create a serene backdrop, encouraging locals and visitors alike to appreciate the slow shift in the season.
Weather in Sierre varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Sierre, focusing on differences in temperature, rainfall, humidity, and UV levels.
September and January exhibit stark contrasts in weather. In September, the temperature ranges from a chilly -5°C (23°F) to a mild 22°C (72°F), with an average of 9°C (49°F) and 12 days of precipitation totaling 90 mm (3.6 in). The humidity sits at a comfortable 81%. In contrast, January brings much colder conditions, with temperatures plunging to a minimum of -27°C (-17°F) and reaching a maximum of 6°C (44°F), averaging -9°C (16°F). This month experiences higher precipitation levels of 135 mm (5.3 in) over just 10 days, with humidity slightly rising to 91%. For a closer look at what January has to offer, check out Sierre weather in January.
In September, the weather is generally milder, with temperatures ranging from a minimum of -5°C (23°F) to a maximum of 22°C (72°F) and an average of 9°C (49°F). This month experiences approximately 90 mm (3.6 in) of precipitation over 12 days and carries a humidity level of 81%. In contrast, February is significantly colder, featuring temperatures that dip to a minimum of -23°C (-8°F) and peak at 11°C (52°F), averaging -5°C (23°F). Precipitation remains slightly higher at 95 mm (3.8 in) across 11 days, while humidity increases to 89%. For more detailed insight, you can refer to Sierre weather in February.
September and March present contrasting weather patterns. In September, temperatures range from a minimum of -5°C (23°F) to a pleasant maximum of 22°C (72°F), with an average of 9°C (49°F). The month sees around 90 mm (3.6 in) of precipitation over 12 days, and humidity sits at 81%. In stark contrast, March experiences much colder temperatures, with a minimum of -25°C (-12°F) and an average of -2°C (29°F), reaching a maximum of 14°C (57°F). Precipitation is higher at 122 mm (4.8 in) over 15 days, and humidity increases slightly to 87%. For a more detailed look at March weather, you can view Sierre weather in March.
In September, the weather tends to be milder compared to April, with average temperatures around 9°C (49°F) and maximums reaching up to 22°C (72°F). This month experiences less cold, showcasing a minimum of -5°C (23°F) and slightly higher humidity at 81%. Precipitation is also more frequent in September, with 90 mm (3.6 in) over 12 days.
In contrast, April is characterized by cooler conditions, as it has an average temperature of only 3°C (37°F) and a maximum of 17°C (63°F). The minimum temperature can drop significantly to -17°C (1°F), indicating a sharper chill to the air. Though April sees slightly less rainfall at 81 mm (3.2 in) over 11 days, the humidity remains relatively high at 84%. For those interested in specific weather details for April, Sierre weather in April offers additional insights.
In September, temperatures in Sierre range from a low of -5°C (23°F) to a pleasant high of 22°C (72°F), with an average of 9°C (49°F). The month experiences around 90 mm (3.6 in) of precipitation over 12 days, coupled with a humidity level of 81%. In contrast, May sees cooler minimum temperatures at -16°C (4°F) but shares the same maximum temperature of 22°C (72°F), with a slightly lower average of 6°C (43°F). However, May is notably wetter, with 160 mm (6.3 in) of rainfall spread across 20 days, while humidity remains similar at 80%. For more detailed insights, you can explore Sierre weather in May.
In comparing the weather of September and June, notable differences emerge. September typically features a wider temperature range, with minimums dipping as low as -5°C (23°F) and maximums reaching up to 22°C (72°F), while the average temperature settles around 9°C (49°F). In contrast, June enjoys milder conditions, with temperatures ranging from a minimum of -4°C (25°F) to a maximum of 27°C (81°F), presenting an average of 12°C (53°F). While both months see a fair amount of rainfall, June experiences slightly higher precipitation of 130 mm (5.1 in) over 16 days compared to September’s 90 mm (3.6 in) over 12 days. Humidity levels remain relatively consistent, with September at 81% and June slightly higher at 82%. For more detailed insights, check out Sierre weather in June.
In comparing the weather between July and September, we see notable differences in temperature and precipitation patterns. July features a wider range of temperatures, with minimums around 1°C (34°F) and maximums reaching up to 28°C (82°F), resulting in an average of 14°C (57°F). In contrast, September experiences cooler temperatures, with a minimum of -5°C (23°F) and a maximum of 22°C (72°F), leading to an average of 9°C (49°F). Rainfall is slightly higher in July, with 121 mm (4.8 in) spread over 16 days compared to September's 90 mm (3.6 in) over 12 days. Humidity levels are comparable, with July at 82% and September at 81%. For more detailed insights on July’s weather, you can refer to this link: Sierre weather in July.
In comparing the weather between August and September, notable differences emerge in both temperature and precipitation patterns. September experiences cooler temperatures, with an average of 9°C (49°F) and a maximum of 22°C (72°F), compared to August's warmer average of 13°C (56°F) and maximum of 26°C (80°F). Additionally, September tends to be wetter, recording 90 mm (3.6 in) of precipitation over 12 days, whereas August has 129 mm (5.1 in) across 16 days. Humidity levels are slightly higher in September at 81%, compared to 77% in August, contributing to a more damp feel in the early autumn month. For more detailed insights on August weather, you can refer to Sierre weather in August.
September and October show a noticeable shift in weather patterns as autumn settles in. In September, temperatures range from a minimum of -5°C (23°F) to a maximum of 22°C (72°F), with an average of 9°C (49°F). The precipitation is moderate, totaling 90 mm (3.6 in) over about 12 days, and humidity hovers around 81%. In contrast, October sees a slight drop in temperatures, with minimums hitting -6°C (21°F) and a maximum of 18°C (64°F), leading to an average of 5°C (41°F). Precipitation increases to 135 mm (5.3 in) across 13 days, accompanied by higher humidity levels at 89%. This transition marks October as a cooler and wetter month compared to September. For a detailed look at the weather specifics, check out Sierre weather in October.
September and November present distinctly different weather patterns. In September, temperatures range from a minimum of -5°C (23°F) to a comfortable maximum of 22°C (72°F), with an average of 9°C (49°F). The month sees about 90 mm (3.6 inches) of precipitation over 12 days and maintains a humidity level of 81%. In contrast, November brings colder conditions, with minimum temperatures plunging to -23°C (-10°F) and a maximum of just 14°C (58°F), resulting in an average temperature of -2°C (29°F). Precipitation slightly increases to 98 mm (3.8 inches) over 14 days, accompanied by higher humidity at 89%. For a more detailed look at November's weather, you can visit Sierre weather in November.
The weather in September contrasts sharply with that of December. In September, temperatures range from a minimum of -5°C (23°F) to a pleasant average of 9°C (49°F), peaking at a maximum of 22°C (72°F). With 90 mm (3.6 in) of precipitation over about 12 days and a humidity level of 81%, the month feels relatively mild. In stark contrast, December plunges into much colder temperatures, with a minimum of -30°C (-22°F) and an average of -8°C (18°F), only reaching a maximum of 7°C (45°F). This winter month sees a significant increase in precipitation, totaling 188 mm (7.4 in) across 16 days, and a higher humidity of 91%, contributing to a much chillier atmosphere. For more details on December weather, you can check this link: Sierre weather in December.
As September rolls in, Sierre transforms into a tapestry of shifting weather, offering a unique blend of mild temperatures and crisp air that marks the transition from summer to autumn. While the days are still warm enough to enjoy the outdoors, the evenings cool down significantly, reminding us that winter is on the horizon. With an average humidity of 81% and notable rainfall, September’s weather stands out from the hotter, drier summer months, bringing refreshing changes and vibrant colors to the landscape. For more detailed insights about the region's climate, visit Sierre Climate.