The accident occurred shortly before 1pm as a 66-year-old man was driving his Subaru on the motorway with his wife in the passenger seat toward Vevey in the canton of Vaud, Fribourg cantonal police said in a statement.
At a sport shortly before the exit for Châtel-Saint Denis the chunk of snow dropped on the vehicle, shattering the glass of the windscreen on the passenger’s side, the statement said.
The woman was seriously hurt from the broken glass, police said.
She was transported by hospital for treatment of life-threatening injuries, police said.
The incident was the latest in a series of transportation snafus from a snow storm late last week that hit the region hard, closing roads and forcing cancellation of classes on Friday for 10,000 students in part of the canton of Vaud.
Seven schools closed their doors and six reduced operations in the Côte and Jura regions, police said.
Those schools are planning to reopen on Monday after snow ploughs cleared major roads in the region that were first struck by snow then by high winds that caused drifts.
Cantonal and municipal police responded to 150 accidents and attended to 110 vehicles blocked by snow, the canton's force said.
At the Leysin ski resort in the Vaud Alps, winds gusted up to 100 kilometres on Sunday, forcing operators to close all the lifts for security reasons at 11am, 20 Minutes newspaper reported.
A spokesman for the resort said three lifts were operating again later on Sunday afternoon.
Safety issues remain in forest regions where trees are weighed down by snow.
Authorities advised back country skiers and snow shores to avoid walking in the woods, particularly in areas at an altitude above 800 metres.