[1] Most of the population (as of 2000[update]) speaks French (31,488 or 85.1%) as their first language, German is the second most common (1,878 or 5.1%) and Portuguese is the third (1,029 or 2.8%).

[4] The historical population is given in the following chart:[6] In the 2007 federal election, the most popular party was the CVP which received 37.31% of the vote.

[10] In the 2007 Swiss Council of States election a total of 15,234 votes were cast, of which 1,196 or about 7.9% were invalid.

[11] From the 2000 census[update], 29,644 or 80.1% were Roman Catholic, while 1,708 or 4.6% belonged to the Swiss Reformed Church.

The wettest month is December during which time Sion receives an average of 61 mm (2.4 in) of rain or snow.

The month with the most days of precipitation is August, with an average of 8.2, but with only 55 mm (2.2 in) of rain or snow.

The driest month of the year is April with an average of 36 mm (1.4 in) of precipitation over 5.9 days.