The city is located in the south-west of Switzerland, in the canton of Valais, at 490 meters (1,600 feet), in a valley oriented from west to east, where rainfall is scarcer than in the rest of Switzerland. Furthermore, the amount of sunshine is comparable to that of the Canton of Ticino. A short distance away we find the ski resort of Crans-Montana, which is located at 1,500 meters (4,900 feet) above sea level.
is cold. Cold air tends to stagnate in the valley, and at night, the temperature often drops below freezing, but during the day, the sun is seen a little more often than in the cities of the Swiss plateau such as Bern or Zurich. There may be relatively mild periods, when Atlantic currents prevail, and other colder periods, when the temperature drops below freezing. On average, 44 cm (17 in) of snow fall per year.
Sometimes, there can be cold spells, in which temperatures can drop as low as -10 °C (14 °F) or even below. The coldest record is -21 °C (-6 °F) and was set in January 1968 and in January 1979.
, the temperatures are generally pleasant and lend themselves to outdoor activities, although sometimes there can be rains and thunderstorms.
At times, hot periods can occur, generally of short duration, which in recent years are becoming more frequent due to global warming, and in which the temperature can exceed 32 °C (90 °F). The highest record is 38 °C (100.4 °F) and was set in July 2015 and in July 2019. In 2022, the temperature reached 37 °C (98.6 °F) in June, 36.3 °C (97.3 °F) in July and 36.2 °C (97.2 °F) in August.
to visit Sion is from mid-May to mid-September, since it is the warmest and sunniest of the year. However, we cannot exclude some rain, or a bit of cool weather, or even cold, especially in May and early June.
. Here are the average temperatures.
January, the coldest month of the year, is generally a cold month. The average temperature is of
1 °C, with a minimum of
-3.1 °C and a maximum of
5.1 °C.

On the coldest nights of the month, the temperature usually drops to around
-9 °C. However, it dropped to
-16 °C in January 2005.

On the warmest days of the month, the temperature usually reaches around
11 °C. However, it reached
16.8 °C in January 2007.

Precipitation amounts to
50 mm, distributed over 7 days.
The day lasts on average 9 hours and 5 minutes.

There are on average 3 hours of sunshine per day. So, the sun shines 32% of the time.
The average humidity is 77%. Hence, the air is normally humid.
The average wind speed is of
5.6 kph.
February is generally a cold month. The average temperature is of
2.9 °C, with a minimum of
-2 °C and a maximum of
7.9 °C.

On the coldest nights of the month, the temperature usually drops to around
-7.5 °C. However, it dropped to
-15.9 °C in February 1999.

On the warmest days of the month, the temperature usually reaches around
15 °C. However, it reached
21 °C in February 2017.

Precipitation amounts to
40 mm, distributed over 6 days.
The day lasts on average 10 hours and 25 minutes.

There are on average 4.5 hours of sunshine per day. So, the sun shines 44% of the time.
The average humidity is 69%.
The average wind speed is of
6.6 kph.
March is generally a quite mild month. The average temperature is of
7.7 °C, with a minimum of
1.7 °C and a maximum of
13.7 °C.

On the coldest nights of the month, the temperature usually drops to around
-3.5 °C. However, it dropped to
-9.8 °C in March 2005.

On the warmest days of the month, the temperature usually reaches around
21 °C. However, it reached
24.9 °C in March 2004.

Precipitation amounts to
35 mm, distributed over 6 days.
The day lasts on average 12 hours and 0 minutes.

There are on average 6 hours of sunshine per day. So, the sun shines 51% of the time.
The average humidity is 60%.
The average wind speed is of
8.8 kph.
April is generally a mild month. The average temperature is of
11.4 °C, with a minimum of
5.1 °C and a maximum of
17.8 °C.

On the coldest nights of the month, the temperature usually drops to around
0 °C. However, it dropped to
-2 °C in April 2003.

On the warmest days of the month, the temperature usually reaches around
25 °C. However, it reached
29 °C in April 2018.

Precipitation amounts to
35 mm, distributed over 5 days.
The day lasts on average 13 hours and 35 minutes.

There are on average 7 hours of sunshine per day. So, the sun shines 51% of the time.
The average humidity is 56%.
The average wind speed is of
9.8 kph.
May is generally a very mild month. The average temperature is of
15.5 °C, with a minimum of
9.2 °C and a maximum of
21.8 °C.

On the coldest nights of the month, the temperature usually drops to around
4 °C. However, it dropped to
-0.4 °C in May 1991.

On the warmest days of the month, the temperature usually reaches around
29.5 °C. However, it reached
35.1 °C in May 2009.

Precipitation amounts to
50 mm, distributed over 8 days.
The day lasts on average 15 hours and 0 minutes. So the days are long.

There are on average 7 hours of sunshine per day. So, the sun shines 48% of the time.
The average humidity is 60%.
The average wind speed is of
9.7 kph.
June is generally a warm month. The average temperature is of
19.2 °C, with a minimum of
12.8 °C and a maximum of
25.5 °C.

On the coldest nights of the month, the temperature usually drops to around
7.5 °C. However, it dropped to
1.5 °C in June 2006.

On the warmest days of the month, the temperature usually reaches around
32.5 °C. However, it reached
36.7 °C in June 2019.

Precipitation amounts to
50 mm, distributed over 7 days.
The day lasts on average 15 hours and 40 minutes. So the days are long. June 21, the summer solstice, is the longest day of the year in the Northern Hemisphere.

There are on average 8.5 hours of sunshine per day. So, the sun shines 54% of the time.
The average humidity is 60%.
The average wind speed is of
10 kph.
July, the warmest month of the year, is generally a warm month. The average temperature is of
20.9 °C, with a minimum of
14.4 °C and a maximum of
27.3 °C.

On the coldest nights of the month, the temperature usually drops to around
9.5 °C. However, it dropped to
6.6 °C in July 1996.

On the warmest days of the month, the temperature usually reaches around
34 °C. However, it reached
38 °C in July 2015.

Precipitation amounts to
65 mm, distributed over 8 days.
The day lasts on average 15 hours and 20 minutes. So the days are long.

There are on average 8.5 hours of sunshine per day. So, the sun shines 56% of the time.
The average humidity is 61%.
The average wind speed is of
9.8 kph.
August is generally a warm month. The average temperature is of
20.3 °C, with a minimum of
14 °C and a maximum of
26.5 °C.

On the coldest nights of the month, the temperature usually drops to around
8.5 °C. However, it dropped to
3.9 °C in August 1995.

On the warmest days of the month, the temperature usually reaches around
33 °C. However, it reached
37.2 °C in August 2003.

Precipitation amounts to
60 mm, distributed over 8 days.
The day lasts on average 14 hours and 5 minutes. So the days are long.

There are on average 8 hours of sunshine per day. So, the sun shines 57% of the time.
The average humidity is 64%.
The average wind speed is of
8.6 kph.
September is generally a very mild month. The average temperature is of
16.2 °C, with a minimum of
10.3 °C and a maximum of
22 °C.

On the coldest nights of the month, the temperature usually drops to around
5.5 °C. However, it dropped to
1 °C in September 1995.

On the warmest days of the month, the temperature usually reaches around
28 °C. However, it reached
33 °C in September 2009.

Precipitation amounts to
40 mm, distributed over 6 days.
The day lasts on average 12 hours and 30 minutes.

There are on average 7 hours of sunshine per day. So, the sun shines 55% of the time.
The average humidity is 69%.
The average wind speed is of
8 kph.
October is generally a mild month. The average temperature is of
11.5 °C, with a minimum of
6 °C and a maximum of
16.9 °C.

On the coldest nights of the month, the temperature usually drops to around
0.5 °C. However, it dropped to
-4.6 °C in October 1997.

On the warmest days of the month, the temperature usually reaches around
23.5 °C. However, it reached
28 °C in October 2009.

Precipitation amounts to
40 mm, distributed over 6 days.
The day lasts on average 10 hours and 55 minutes.

There are on average 5 hours of sunshine per day. So, the sun shines 48% of the time.
The average humidity is 74%. Hence, the air is normally humid.
The average wind speed is of
6.3 kph.
November is generally a quite cold month. The average temperature is of
5.5 °C, with a minimum of
1 °C and a maximum of
10.1 °C.

On the coldest nights of the month, the temperature usually drops to around
-4.5 °C. However, it dropped to
-12.3 °C in November 2005.

On the warmest days of the month, the temperature usually reaches around
18 °C. However, it reached
21 °C in November 2008.

Precipitation amounts to
50 mm, distributed over 7 days.
The day lasts on average 9 hours and 25 minutes.

There are on average 3 hours of sunshine per day. So, the sun shines 33% of the time.
The average humidity is 76%. Hence, the air is normally humid.
The average wind speed is of
5.5 kph.
December is generally a cold month. The average temperature is of
1.3 °C, with a minimum of
-2.5 °C and a maximum of
5.1 °C.

On the coldest nights of the month, the temperature usually drops to around
-8.5 °C. However, it dropped to
-12.6 °C in December 2005.

On the warmest days of the month, the temperature usually reaches around
12 °C. However, it reached
17.5 °C in December 2003.

Precipitation amounts to
70 mm, distributed over 8 days.
The day lasts on average 8 hours and 40 minutes. December 21, the winter solstice, is the shortest day of the year in the Northern Hemisphere.

There are on average 2 hours of sunshine per day. So, the sun shines 25% of the time.
The average humidity is 80%. Hence, the air is normally humid.
The average wind speed is of
5.4 kph.