Heavy rains and wind gusts of up to 90 kilometres an hour pounded British Columbia's South Coast overnight, prompting a series of flood warnings and promises of more to come.

Environment Canada says the coast will continue to be whipped with a strong frontal system, bringing an additional 30 to 90 millimeters of rain to the already soggy coastal region in the next 24 hours.

The largest amounts of rain are expected in southern Howe Sound, Metro Vancouver and the North Shore mountains. Weather advisories previously in effect for Whistler and Pemberton have been dropped.

Flood watch

The B.C. Environment River Forecast centre issued a flood watch advisory Monday morning for Howe Sound, including Squamish, as well as west and central Vancouver Island, including Port Alberni and Ucluelet to Zeballos.

North and West Vancouver, Coquitlam, Maple Ridge and Mission are also under flood watch, with the centre expecting water levels may exceed their river banks, spilling over into adjacent areas.

While flooding began in some small creeks on North Shore mountains Monday morning, officials say river levels aren't worrying. The largest rivers - Seymour, Coquitlam, Alouette and Stave - are all "well below" levels of concern.

The upper Coquitlam River gauge recorded 150 millimeters of rain over the past 24 hours - the largest measurement recorded in B.C.'s Lower Mainland.

Vancouver Island

Heavy rain, combined with snow melt, prompted flood warnings for multiple Vancouver Island rivers, including Gold, Heber, Oyster and Salmon Rivers at Sayward.

Some parts of the Island recorded up to 410 millimeters of rain over the past 30 hours.

The Nanaimo, Englishman and Cowichan Rivers are all near two-year return period levels and are rising. High tide could force localized flooding along their lower banks today, the river centre predicts.

Power out

High winds cut power to more than 16,000 BC Hydro customers overnight, with thousands still without power Monday morning.

Fallen power lines closed Highway 20 at Bella Coola and Highway 4 near Port Alberni on Vancouver Island overnight. Road workers spent most of the morning cleaning up a mudslide on Highway 19 north of Sayward on Vancouver Island.

More to come?

Environment Canada predicts the heavier rain will ease by Tuesday with unsettled weather patterns and lighter rains persisting through the week.

The River Forecast Centre will issue a provincial update early Tuesday morning or if conditions worsen.