Close to 50 centimetres of snow fell on Saturday in areas of the southern canton of Ticino and the eastern canton of Graubünden over 1,500 metres, Meteonews reported.
Heavy snow disrupted rail traffic on the Matterhorn Gotthard Bahn line between Realp and Hospental in the canton of Uri, the railway announced.
Elsewhere, the threat of an avalanche closed the Rhaetian Railway between Bergün and Samedan on the line between Chur and St. Moritz in the canton of Graubünden.
The Glacier Express and Bernina Express trains were being rerouted via Vereina and passengers were warned on Sunday to expect longer travelling times.
PostBus service was suspended on routes in the St. Moritz area, such as the Julier-Express between Bivio and St. Moritz, because of the heavy snowfall.
Meanwhile, no trains were operating on Sunday on the Rhaetian Railway line between Pontresina and Poschiavo on the St. Moritz-Poschiavo route.
“We advise against travelling for the time being,” Swiss Federal Railways (SBB) advised passengers planning to take the train between the two communities.
The risk of avalanches made the duration of disruption “indefinite”, SBB said.
“The precipitation has been clearly more heavy in the east of the country,” a spokesman from MeteoSwiss, the national weather office, told the ATS news agency.
Snow was falling at levels as low as 600 and 700 metres, while rain fell in lower-lying regions, the spokesman said.
Between 16 and 30 centimetres of snow were recorded in the Val d’Illiez in the canton of Valais, and less than 15 centimetres at Chateaux d’Oex in the Vaud Alps.
The danger of avalanches remained high in the Alps from Sion (Valais) to Chur (Graubünden), as well as Andermatt (Uri) and St. Moritz (Graubünden).
After recording temperatures as high as 27 degrees last Monday, Ticino, the warmest place in the country, saw highs rise to no higher than 10 degrees on Sunday, MeteoSwiss said.
Elsewhere, the mercury struggled to reach eight degrees in Geneva, Lausanne and Sion, the capital of Valais.
Wintry conditions are expected to continue until Tuesday before milder conditions return, MeteoSwiss said.