Sion has an average of 82.6 days of rain or snow per year and on average receives 598 mm (23.5 in) of precipitation. The wettest month is December during which time Sion receives an average of 61 mm (2.4 in) of rain or snow. During this month there is precipitation for an average of 7.4 days. 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
