At least one person has died in torrential rains that forced thousands in western Canada to evacuate their homes and trapped motorists in mudslides, according to federal police.

Search and rescue teams recovered the body of a woman from a mudslide near Lillooet, 250km north of Vancouver, the Royal Canadian Mounted Police said.

Staff Sergeant Janelle Shoihet added that investigators have received two missing person reports, but that they believe "there may have been other occupied vehicles that were lost in the slide".

"The total number of people and vehicles unaccounted for has not been confirmed," she said.

Mudslides, rocks and debris washed away several highways leading to Vancouver, trapping hundreds of motorists who were rescued by military helicopters by nightfall yesterday.

Local television showed video footage of the Trans Canada highway connecting the coastal city to the rest of the country inundated. A bridge was also washed out.

Hougen Park is submerged after rainstorms lashed Abbotsford, British Columbia

Other routes have also been closed, according to traffic information service Drive BC, which said on Twitter: "Highways are closed until further notice".

Environment Canada said up to 250 millimetres of rain - what the region normally gets in a month - fell on Sunday and yesterday in and around Vancouver, which was also hit last week by a rare tornado.

Emergency centres were set up for displaced residents.

"Please stay safe," Prime Minister Justin Trudeau said in a Twitter message.

"We're ready to provide whatever assistance is needed as you deal with and recover from the flooding and this extreme weather," he said.

Construction of the Trans Mountain pipeline connecting the Alberta oil sands to the Pacific coast was also paused, a company spokesperson said, "due to widespread flooding and debris flows."

Meteorologist Tyler Hamilton commented on social media that the city of Abbotsford, outside Vancouver, in the past 140 days had experienced both its warmest and wettest days ever.

The extreme weather comes after British Columbia suffered record-high temperatures over the summer that killed more than 500 people, as well as wildfires that destroyed a town.