Climate and monthly weather forecastSion, Switzerland
Climate and monthly weather forecast
The climate of Sion
Sion, a Swiss city nestled in the heart of the Rhone valley, falls under the ET classification in the Köppen climate structure, indicating a tundra climate. This type of weather is characterized by often harsh winters, brief and mildly warm summers, and significant variations in humidity, rain, snow, daylight, and sunshine throughout the year.Sion's weather ranges from the bitterly cold winters where the lowest temperature can be as chilling as -11°C (12.2°F) in January and February, to only moderately warm summers with the highest temperature recorded around 16.7°C (62.1°F) in August. Humidity remains relatively high throughout the year, peaking at around 90% in March and dropping to 79% in July and August.
In terms of precipitation, Sion experiences both rainfall and snowfall. The city gets its maximum rainfall of about 177mm (6.97") in May whereas the least, around 76mm (2.99"), is in September. The frequency of rainfall is also the highest in May with about 25.8 days. Snowfall is more common from November to April, with a peak in January and February, accumulating as much as 159mm (6.26"). Regarding sunshine, Sion enjoys up to 9.8 hours of sunlight in July and August.
The best time to visit Sion
Considering the temperature and sunshine hours, the best time for tourists to visit Sion would be from late spring to early autumn. Specifically, these months include May to October when the temperature ranges from a pleasant 8.7°C (47.7°F) to a comfortable 16.7°C (62.1°F). Moreover, these months also experience the highest daylight hours, extending from 13.6 hours in April to 15.7 hours in June, which allows ample time for outdoor activities. July and August, along with the highest temperatures, bring the most sunshine, averaging about 9.8 hours daily, and consequently provide the best climate for a visit.The worst time to visit Sion
The period between November to April would be less ideal for visitation as it marks the cold season in Sion. During this period, the temperature typically drops from 2.5°C (36.5°F) in November and reaches its lowest, -11°C (12.2°F), in January. Furthermore, daylight hours reduce significantly, registering a minimum of 8.7 hours in December. These months are also prone to heavy snowfall, making it highly unfavorable for outdoor-oriented travel, unless winter sports and snow expeditions are the primary goal.Spring weather in Sion
From March to May, Sion enters its spring season. The temperatures start to rise from the winter lows, averaging between -7.7°C (18.1°F) to 8.7°C (47.7°F). While March and April still witness occasional snowfall, by May, it almost completely fades away. However, with the melting snow, there is an increase in rainfall volume and frequency, reaching a peak in May. Despite these showers, the amount of sunshine begins to improve significantly during this transitional period, offering more pleasant conditions towards the end of spring.Summer weather in Sion
Summer in Sion brings a respite from the harsh winters with the mercury level rising to an average high of 16.7°C (62.1°F). The heat, however, is moderate and far from sweltering. June to August witnesses a slight drop in humidity, down to 79%, which contributes to the overall comfort. There is a marginal dip in rainfall, but it is the abundance of sunshine, up to approximately 10 hours in the warmest months, that truly highlights the summer season in Sion.Autumn weather in Sion
The autumn months, namely September, October, and November, witness a gradual cooling in temperature from the summer warmth. With temperatures ranging from 12.3°C (54.1°F) to 2.5°C (36.5°F), the weather slowly transitions towards the impending winter chill. Rainfall continues to drop during these months, reaching its yearly low in September. However, sunshine hours also start decreasing, indicating shorter days.Winter weather in Sion
Winter grips Sion firmly between December and February, as temperatures plummet, falling up to -11°C (12.2°F). Snowfall increases dramatically during these months, particularly in December and January, when it reaches its highest volume. This, combined with the reduced daylight and lower visibility, generally covers Sion in a frosty haze for the significant part of winter. However, this season offers its unique charm and wonder, especially for those intrigued by winter landscapes or interested in winter sports.Weather in January
Beginning the year, the weather in Sion, Switzerland is typically cold, with January seeing temperatures from -11°C (12.2°F) to -2.5°C (27.5°F) on average. The city experiences numerous days with snow, aligning with the overall Swiss winter atmosphere. Weather in January »Weather in February
In consistent pattern with January, February's weather in Sion features the similar average temperatures from -11°C (12.2°F) to -2.3°C (27.9°F). The month, however, holds marginally more daylight hours, marking subtle inroads towards Swiss spring. Weather in February »Weather in March
Transitioning into the warmer months, March sees a slight rise in average temperatures which now range from -7.7°C (18.1°F) to 0.9°C (33.6°F). The month is characterized by increased daylight hours and a decrease in snowfall compared to February. Weather in March »Weather in April
April truly heralds the arrival of spring in Sion, with the temperature increase being quite noticeable, ranging from -3.2°C (26.2°F) to 5°C (41°F). This month registers a significant reduction in snowfall, with precipitation occurring mainly as rain, the rainfall peaking at 91mm (3.58") over 22.6 days. Weather in April »Weather in May
May's weather brings warmer days to Sion, Zurich, with temperatures continuing their northward move. Sunshine hours also see a considerable surge compared to April, marking plenteous outdoor opportunities. While rainfall is abound, the frequency of rainy days is significantly less than the previous month, painting a generally favorable weather canvas. Weather in May »Weather in June
In June, summer starts to settle in with the average temperatures now ranging between 4.3°C (39.7°F) to 13.9°C (57°F). The weather conditions are generally pleasant, encouraging outdoor activities and exploration of the picturesque Swiss landscapes. Weather in June »Weather in July
As one of the two warmest months in Sion, July experiences average temperatures between 6.3°C (43.3°F) and 16.5°C (61.7°F). With the city now well into summer, the month registers the highest UV index figure for the year, meaning sunscreen becomes a must-have item. Weather in July »Weather in August
August's weather in Sion, Switzerland echos that of the previous month, with the average temperatures dancing between 6.4°C (43.5°F) and 16.7°C (62.1°F). The month symbolizes the peak summer period, scoring equal to July in UV index evaluations. Weather in August »Weather in September
Come September, Sion starts to transition from summer towards the autumn season, experiencing temperatures that range from 3.3°C (37.9°F) to 12.3°C (54.1°F). Despite the shortening daylight hours, the city continues to enjoy many sunny days. Weather in September »Weather in October
October's weather in Sion, Switzerland bears the true mark of autumn. Despite cooler temperatures, the city often enjoys bright, clear days amid colourful vistas of turning leaves. This is the period where the wind speed starts to pick up slightly, adding to the cool feel of the weather. Weather in October »Weather in November
During November, the weather in Sion becomes visibly chillier, lending more credence to the arrival of the Swiss winter. The city witnesses a drop in temperatures compared to October as well as an increase in precipitation, a mix of rain and snow towards the end month. Weather in November »Weather in December
In December, Sion, Switzerland braces itself for full-blown winter, with temperatures plummeting to between -9.5°C (14.9°F) and -1.2°C (29.8°F). This month records the highest snowfall at 156mm (6.14") over 7.2 days, turning the city into a winter wonderland. Weather in December »Updated: Feb 3, 2024
Published by: Weather Atlas | About Us
Data Sources | Weather Forecasting & Climate
Published by: Weather Atlas | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
January stands out as Sion's coldest month, with an average high-temperature of -2.5°C (27.5°F) and a low-temperature of -11°C (12.2°F).
In Sion, Switzerland, during the entire year, the rain falls for 233.7 days and collects up to 1378mm (54.25") of precipitation.
Months with snowfall are January through May, September through December.
Throughout the year, in Sion, Switzerland, there are 40.9 snowfall days, and 716mm (28.19") of snow is accumulated.
January has the least sunshine of the year in Sion, Switzerland, with an average of 4.7h of sunshine.
January and November, with an average maximum UV index of 1, are months with the lowest UV index in Sion, Switzerland.
The month with the most snowfall in Sion, Switzerland, is February, when snow falls for 10.2 days and typically aggregates up to 167mm (6.57") of snow.
With an average relative humidity of 90%, March is the most humid month.
May is the month with the most rainfall. Rain falls for 25.8 days and accumulates 177mm (6.97") of precipitation.
June through August are months without snowfall.
With an average of 15h and 42min of daylight, June has the longest days of the year.
The months with the highest UV index in Sion are June and July, with an average maximum UV index of 4.
July and August, with an average relative humidity of 79%, are the least humid months in Sion.
July and August, with an average of 9.8h of sunshine, are months with the most sunshine.
Sion, Switzerland, experiences its average highest temperatures in August, reaching a peak of 16.7°C (62.1°F) and a minimum of 6.4°C (43.5°F).
The month with the least rainfall in Sion, Switzerland, is September, when the rain falls for 20.2 days and typically collects 76mm (2.99") of precipitation.
On Sunday, 27. October 2024, at 03:00, Daylight Saving Time ends, and the time zone changes from CEST to CET. The next Daylight Saving Time starts on Sunday, 30. March 2025, at 02:00, and the time zone reverts from CET to CEST.
With an average of 8h and 42min of daylight, December has the shortest days of the year in Sion.
Average temperature
Sion, Switzerland
The warmest month (with the highest average high temperature) is August (16.7°C).
The month with the lowest average high temperature is January (-2.5°C).
The month with the highest average low temperature is August (6.4°C).
The coldest months (with the lowest average low temperature) are January and February (-11°C).
Average pressure
Sion, Switzerland
- Average pressure in January:
1019.2mbar - Average pressure in February:
1017.3mbar - Average pressure in March:
1016.8mbar - Average pressure in April:
1015.2mbar - Average pressure in May:
1015.7mbar - Average pressure in June:
1016.2mbar
- Average pressure in July:
1016.8mbar - Average pressure in August:
1017.6mbar - Average pressure in September:
1018.2mbar - Average pressure in October:
1018.3mbar - Average pressure in November:
1015.8mbar - Average pressure in December:
1020.9mbar
The month with the highest atmospheric pressure is December (1020.9mbar).
The month with the lowest atmospheric pressure is April (1015.2mbar).
Average wind speed
Sion, Switzerland
- Average wind speed in January:
8km/h - Average wind speed in February:
7.9km/h - Average wind speed in March:
8.1km/h - Average wind speed in April:
7.4km/h - Average wind speed in May:
7.2km/h - Average wind speed in June:
6.9km/h
- Average wind speed in July:
6.6km/h - Average wind speed in August:
6.2km/h - Average wind speed in September:
6.5km/h - Average wind speed in October:
7.3km/h - Average wind speed in November:
8km/h - Average wind speed in December:
8.3km/h
The windiest month (with the highest average wind speed) is December (8.3km/h).
The calmest month (with the lowest average wind speed) is August (6.2km/h).
Average humidity
Sion, Switzerland
The month with the highest relative humidity is March (90%).
The months with the lowest relative humidity are July and August (79%).
Average rainfall
Sion, Switzerland
- Average rainfall in January:
99mm - Average rainfall in February:
89mm - Average rainfall in March:
101mm - Average rainfall in April:
91mm - Average rainfall in May:
177mm - Average rainfall in June:
155mm
The wettest month (with the highest rainfall) is May (177mm).
The driest month (with the least rainfall) is September (76mm).
Average rainfall days
Sion, Switzerland
- Average rainfall days in January:
14.8 days - Average rainfall days in February:
13.8 days - Average rainfall days in March:
19.1 days - Average rainfall days in April:
22.6 days - Average rainfall days in May:
25.8 days - Average rainfall days in June:
25.3 days
- Average rainfall days in July:
24.7 days - Average rainfall days in August:
22.3 days - Average rainfall days in September:
20.2 days - Average rainfall days in October:
15 days - Average rainfall days in November:
16.2 days - Average rainfall days in December:
13.9 days
The month with the highest number of rainy days is May (25.8 days).
The month with the least rainy days is February (13.8 days).
Average snowfall
Sion, Switzerland
The month with the highest snowfall is February (167mm).
The months with the least snowfall are June, July and August (0mm).
Average snowfall days
Sion, Switzerland
- Average snowfall days in January:
9.5 days - Average snowfall days in February:
10.2 days - Average snowfall days in March:
7.2 days - Average snowfall days in April:
2.7 days - Average snowfall days in May:
0.3 days - Average snowfall days in June:
0 days
- Average snowfall days in July:
0 days - Average snowfall days in August:
0 days - Average snowfall days in September:
0.1 days - Average snowfall days in October:
0.3 days - Average snowfall days in November:
3.4 days - Average snowfall days in December:
7.2 days
The month with the highest number of snowfall days is February (10.2 days).
The months with the least snowfall days are June, July and August (0 days).
Average daylight / Average sunshine
Sion, Switzerland
- Average daylight in January:
9h and 6min - Average daylight in February:
10h and 24min - Average daylight in March:
11h and 54min - Average daylight in April:
13h and 36min - Average daylight in May:
15h and 0min - Average daylight in June:
15h and 42min
- Average daylight in July:
15h and 24min - Average daylight in August:
14h and 6min - Average daylight in September:
12h and 30min - Average daylight in October:
10h and 54min - Average daylight in November:
9h and 30min - Average daylight in December:
8h and 42min
The month with the longest days is June (Average daylight: 15h and 42min).
The month with the shortest days is December (Average daylight: 8h and 42min).
- Average sunshine in January:
4h and 42min - Average sunshine in February:
4h and 54min - Average sunshine in March:
5h and 42min - Average sunshine in April:
7h and 54min - Average sunshine in May:
8h and 12min - Average sunshine in June:
9h and 36min
- Average sunshine in July:
9h and 48min - Average sunshine in August:
9h and 48min - Average sunshine in September:
8h and 18min - Average sunshine in October:
6h and 36min - Average sunshine in November:
5h and 12min - Average sunshine in December:
4h and 54min
The months with the most sunshine are July and August (Average sunshine: 9h and 48min).
The month with the least sunshine is January (Average sunshine: 4h and 42min).
Average sunshine days
Sion, Switzerland
- Average sunshine days in January:
11.6 days - Average sunshine days in February:
8.1 days - Average sunshine days in March:
7.5 days - Average sunshine days in April:
4.6 days - Average sunshine days in May:
3.4 days - Average sunshine days in June:
2.8 days
- Average sunshine days in July:
3.4 days - Average sunshine days in August:
5.4 days - Average sunshine days in September:
7.6 days - Average sunshine days in October:
13.5 days - Average sunshine days in November:
10.7 days - Average sunshine days in December:
12.6 days
The month with the most sunshine days is October (13.5 days).
The month with the least sunshine days is June (2.8 days).
Average UV index
Sion, Switzerland
The months with the highest UV index are June and July (UV index 4).
The months with the lowest UV index are January and November (UV index 1).
Average cloud cover
Sion, Switzerland
The months with the most cloud cover are February and March (Cloud cover 53).
The month with the least cloud cover is October (Cloud cover 37).
Average visibility
Sion, Switzerland
The months with the highest visibility are June, July, August, October and November (8km).
The months with the lowest visibility are January, February and March (6km).
