British Columbia’s River Forecast Centre issued a flood watch for southern Vancouver Island and the Englishman River on Friday.
The alert adds to a high-streamflow advisory already in place for the island, South Coast and Lower Mainland.
The bulletin comes amid concerns about heavy rain forecast throughout the weekend, combined with accumulations of snow already on the ground.
“Heavy, warmer rain falling on the snow packs may cause large volumes of snowmelt, which would induce extra flooding risks to the stream systems in south Vancouver Island,” the forecast centre warned.
Rain and snowmelt could push streamflows on some southern Vancouver Island waterways over the five-year return period this weekend and into early next week, it said.
People are being advised to steer clear of fast-flowing rivers and potentially unstable riverbanks across the entire South Coast.
Much of the province remained under extreme weather alerts on Friday.
Earlier in the day, Environment Canada issued a rainfall warning for Metro Vancouver, forecasting between 25 and 50 millimetres of rain for most of the region, and between 60 and 90 mm for the North Shore and northern parts of Coquitlam and Maple Ridge.
The heavy rain and warmer air are expected to arrive on the South Coast on Saturday, and could lead to localized flooding in low-lying areas, the national weather and climate agency said.
The Fraser Valley remained under a winter storm warning Friday, while the Greater Victoria region was under a freezing rain warning.
People are being urged to stay off the roads unless absolutely necessary.