Prime Minister Justin Trudeau on Friday visited areas of Canada's Pacific coast hit by catastrophic floods, warning of further climate mayhem as the region braces for more torrential rains.

"This will not be the last crisis Canadians go through," Trudeau told a joint news conference with British Columbia's premier, John Horgan.

"Extreme weather events are going to become more frequent," he said, adding: "We need to address the long term climate change problems," including by cutting CO2 emissions and making infrastructure more resilient.

Heavy rains hit British Columbia in mid-November, causing widespread flooding and mudslides that damaged or destroyed roads and bridges, forced thousands to evacuate their homes and left at least four dead and one missing.

This followed record-high temperatures over the summer that killed more than 500 people in the province, as well as wildfires that destroyed a town.

"We're facing the brunt of climate change, not in the future, but right now," Horgan said.

"Our farms have been flooded, our roads have been washed away and our communities are underwater, and more rain is coming," he said.

Horgan's government on Friday ordered sections of three major highways closed ahead of two more major rain storms expected over the coming days.

Environment Canada has forecast up to 120 millimeters (4.7 inches) of rain over the weekend, warning it could lead to flash floods and washouts.

A second storm is expected to slam the province on Monday.