Climate Overview
The climate in Sion Airport is cool. The average annual temperature is 4°C and approximately 1763mm of precipitation falls per year. Sion Airport receives a notable amount of rainfall throughout the year, including during its driest month. Sion Airport is in the Northern Hemisphere. Summer begins at the end of June and lasts through September. The summer months are: July, August, June. The coldest months are January, December, February, when temperatures can drop to -11°C. Sion Airport experiences heavy snowfall, typically from January through December.
Temperature
Temperatures in Sion Airport vary considerably across the year, with a 31°C difference between the coldest and warmest months. July is the warmest month, though highs remain moderate at 20°C with a mean of 14°C. The coldest month is January, when overnight lows fall to -11°C and the daily average is -7°C. On average, daily temperatures fluctuate by about 10°C between overnight lows and afternoon highs. The sharpest temperature change occurs between October and November, with a 7°C shift in average temperatures.
Precipitation
Sion Airport is a fairly wet location, receiving approximately 1763mm of precipitation annually, which averages out to around 147mm per month. The wettest month is May, averaging 188mm of rainfall. July and June also tend to see above-average precipitation. The driest month is February, with just 102mm. That's 86mm less than May, the wettest month. Rainfall is relatively evenly distributed throughout the year, so there is no pronounced dry or wet season to plan around. Sion Airport receives heavy snowfall, accumulating around 698cm annually from January through December. The snowiest month is January, with approximately 141cm. Winter travel should account for significant snow cover.
Wind
Sion Airport is relatively calm, with an average annual wind speed of 4km/h. For context, sustained winds below 12km/h are generally light, while anything above 25km/h is considered strong. The windiest month is December, averaging 5km/h, though still comfortable for most outdoor activities. The calmest conditions occur in September, with average winds dropping to 4km/h, making it an ideal period for wind-sensitive activities. There is moderate seasonal variation in wind speed, with a 1km/h gap between the calmest and windiest months.
Seasons
1 day until Autumn
It is currently summer in Sion Airport, which began on June 21, 2026. Sion Airport is in the Northern Hemisphere, where spring begins in March, summer in June, autumn in September, and winter in December. The warmest period peaks in July at around 20°C, while the coldest stretch bottoms out in January near -11°C. Autumn is next, beginning on September 23, 2026 (1 days from now).
Spring
Temperatures range from -5 to 12°C. Rainfall is heavy, totalling around 436mm across the season with a monthly average of 145mm. Winds are generally light, averaging 4km/h. An umbrella or waterproof jacket is advisable as spring showers are frequent.
Summer
Temperatures range from 7 to 20°C. Rainfall is heavy, totalling around 511mm across the season with a monthly average of 170mm. Winds are generally light, averaging 4km/h. Comfortable clothing with a light layer for cooler evenings is all you need.
Autumn
Temperatures range from -5 to 15°C. Rainfall is heavy, totalling around 394mm across the season with a monthly average of 131mm. Expect around 125cm of snow accumulation during this period. Winds are generally light, averaging 4km/h. A waterproof jacket and sturdy footwear are recommended as rain becomes more frequent.
Winter
Temperatures range from -11 to 2°C. Rainfall is heavy, totalling around 422mm across the season with a monthly average of 141mm. Expect around 364cm of snow accumulation during this period. Winds are generally light, averaging 5km/h. Heavy layering and insulated outerwear are essential. Exposed skin should be minimised outdoors.
Monthly Climate Data
The table below shows monthly climate averages for Sion Airport based on historical weather data. Min and max temperatures represent typical overnight lows and afternoon highs for each month, shown in degrees Celsius (°C). Precipitation is measured in millimetres (mm) and indicates the average total rainfall per month. Snow is measured in centimetres (cm) and reflects average monthly snowfall accumulation. Wind speed is the average sustained speed in kilometres per hour (km/h). All values are based on averages from over 10 years of historical weather data. The current month is highlighted for quick reference.
