The Coquihalla Highway was closed between Hope and Merritt, B.C. for part of Thursday evening due to severe weather and poor road conditions.
Several dozen drivers were left stranded in their vehicles before the roadway reopened around 10 p.m. PT.
Stefan Rzadzinski and Mike Czaja got stuck near the summit around 4 p.m. on their way from Edmonton to Vancouver.
Rzadzinski said traffic was brought to a standstill.
"A lot of people are outside their cars. The rest are in their cars staying warm," he told CBC News. "Hopefully everyone's got enough gas to make it down the mountain."
Environment Canada also issued snowfall warnings for a number of other major highways in B.C. on Thursday.
"It's really focused on those high elevation mountain passes," said Environment Canada meteorologist Ross MacDonald.
Snow at higher elevations
MacDonald said there weren't too many flurries in the valleys, but you don't have to go too far outside those dips to find substantial snowfall.
More than 30 centimetres of snow was expected between Hope and Merritt, with a heavier accumulation predicted for the summit.
Warnings were also been issued for Eagle Pass to Rogers Pass and along the Sea to Sky highway between Squamish and Whistler.
Drivers told to wait if possible
Not only will the snow affect what you can see, MacDonald said, but it will also build up quickly in some areas. The expert warned drivers to take care on the roads.
There will likely be a weather window Friday with conditions deteriorating again on the weekend, he said.