In Crans-Montana there has always been snow at Christmas: at mid-mountain, 2,200 m, natural snow cover lasted through the holidays in every winter of 1984/85–2013/14, the first 15 winters and the last 15 alike. The season is long, too, averaging 186 days with at least 30 cm of snow. For snowy Christmases the resort beats 76% of resorts in Switzerland and 87% of European ones out of 690: in Switzerland the bar is high, and even a perfect score puts Crans-Montana only in the top quarter.
From November to late May
Usually continuous snow cover in Valais holds here from 21 November to 24 May: you can ski well into spring. The highest run, at 2,878 m, logged 244 such days per season and all 30 snowy Christmases; the lowest run, at 1,503 m, only 19 of 30. Under the RCP4.5 climate scenario, by 2041–2060 there will be 12.4 snowy Christmas days out of 14 instead of 13.7 in the model reference 1986–2005 (methodology); this is climate, not a forecast. Nearby, Anzère also managed 30 of 30 at 1,900 m, Leukerbad-Torrent 28 of 30 at 2,000 m. If snow at Christmas matters to you, pick Crans-Montana: across the 30 winters of the series there was not a single miss.