Environment Canada issued a rainfall warning for Metro Vancouver with some 50 millimetres expected to drench the region on Saturday.
BC Ferries cancelled several sailings between Comox and Powell River because of the weather.
Some sailings between Cortes Island and Quadra Island in the northern Gulf Islands were also cancelled because of heavy rain and strong winds.
Environment Canada said an intense and moist Pacific frontal system will bring heavy downpours to B.C.'s south coast.
Forecasters warn the rain could cause flash floods and water pooling on roads.