Sion Temperature by Month
Sion in Canton of Valais, Switzerland sees significant seasonal temperature differences, with daytime highs between -3°C (27°F) in January and 19°C (66°F) in July, averaging 8°C (46°F) annually. Explore the full monthly breakdown below.
Sion Monthly Temperatures
The climate in Sion is dynamic, ranging widely from very cold in winter to pleasant in summer. Nights are significantly colder, with lows dropping from 8°C (46°F) in July to -13°C (9°F) in January.
The chart below illustrates the average maximum day and minimum night temperatures in Sion by month:
The coldest point of the day usually falls between 4 AM and 6 AM, with temperatures peaking around 3 PM. July, the city's warmest month, gets 270 hours of sunshine.
The chart below shows the average temperature throughout the year:
Temperature: Sion vs Switzerland
The map below shows the annual temperature across Switzerland. You can also select individual months if you want to compare a specific time of year.
very warm
warm
pleasant
moderate
cold
very cold
Sion vs World: Temperature Compared
Sion's average annual maximum temperature is 8°C (46°F). To put that in context, here's how it compares to a few well-known destinations:
Barcelona, Spain has an annual average of around 21°C (70°F), with warm summers and mild, fairly short winters.
Queenstown, New Zealand averages 10°C (50°F) annually — remember seasons are flipped, so its coldest months fall in June and July.
San Francisco, USA averages 19°C (66°F) annually, but with little seasonal variation — summers are often cool and foggy, winters mild.
Melbourne, Australia averages 20°C (68°F) annually — known for unpredictable weather, with four seasons sometimes happening in one day.
What Does the Temperature Feel Like in Sion?
Temperature alone doesn't tell the whole story — humidity plays a big role in how warm or cold it actually feels. High humidity in summer makes the heat feel more intense, particularly once temperatures climb above 25°C. In winter, the same humidity can make cold air feel sharper than the thermometer suggests.
In the cooler months, when temperatures drop below 10°C, high humidity makes the cold feel more cutting than it would in dry conditions.
In Sion, January is the coolest month, with average highs of -3°C (27°F) and humidity around 78% — considered high. For a full picture, see our humidity page.
Climate temperature data is typically calculated as a 30-year average. This smooths out year-to-year variability and gives a more reliable picture of what a place is actually like, rather than what happened in any single unusual year.
The readings come from a range of sources — land-based weather stations, ocean buoys, ships, and satellites. That data is collected by weather services around the world, then pooled, quality-checked, and averaged to produce the climate records you see here.
For cities and regions with significant elevation, altitude is one of the biggest factors shaping local temperatures. As a rule of thumb, temperatures fall by around 6°C for every 1,000 metres gained — so a city at 2,000 metres will typically be around 12°C cooler than a city at sea level in the same region. Higher ground also tends to see more dramatic day-to-night temperature swings, since thinner air loses heat faster after sunset.
For more on Sion's weather — including monthly rainfall, sunshine hours, and humidity — visit our Sion climate page.
