Winter storm warning on Sea to Sky Hwy. amid ‘prolonged’ atmospheric river

A stretch of Highway 99 near Whistler, B.C., is seen in a traffic camera image on March 16, 2026.

Drivers headed onto the Sea to Sky Highway have been warned to expect heavy snow and heavy rain on Monday due to a “prolonged” atmospheric river over B.C.’s South Coast.

Environment and Climate Change Canada has issued a yellow warning for the busy route between Squamish and Whistler, anticipating up to 20 centimetres of snowfall by midday.

“Weather in the mountains can change suddenly, resulting in hazardous driving conditions,” reads the warning, which was sent at 5:12 a.m. “Prepare for quickly deteriorating travel conditions.”

The snow is expected to give way periods of heavy rain from Monday afternoon to Wednesday, totalling up to 70 millimetres and potentially creating addition problems, according to the weather agency.

ECCC cautioned the heavy rain combined with mountain snow melt “may lead to very enhanced responses in river systems and potential for flooding.”

There could be “extensive water pooling on roads and washouts,” along with “enhanced risk of landslides due to saturation of landscapes,” according to the warning.

The heaviest rain is expected Monday night and Tuesday night, ECCC said.