Much of British Columbia's south coast is bracing for stormy weather as Environment Canada says a "potent and impactful" storm will bring heavy rain to Metro Vancouver.

Environment Canada is also warning drivers on the Sea to Sky Highway from Squamish to Whistler to exercise caution due to heavy rains raising the risk of flooding and landslides along the route. The rainfall warning says an atmospheric river is set to make landfall on the province's southern coast today, bringing as much as 150 millimetres of rain to Western Vancouver Island. Meanwhile, Inland Vancouver Island, the Howe Sound region and parts of Metro Vancouver, including the North Shore, Coquitlam and Maple Ridge, are expecting up to 100 millimetres of rain from the storm.

The forecast says the rest of Metro Vancouver could get up to 70 millimetres of rain today before the storm eases on Tuesday morning. Environment Canada also says motorists on the Coquihalla Highway from Hope to Merritt should be cautious due to the possibility of snow mixed with rain on the roads.

The province's River Forecast Centre has issued high streamflow advisories for the entire southwestern region of British Columbia, encompassing all of Vancouver Island, the Lower Mainland and the south coast.