A rainfall warning is in effect for west Vancouver Island and east Vancouver Island.
Since Monday morning, west Vancouver Island has been under the warning. Environment Canada said a frontal system over the B.C. central coasts will move southward today.
By Monday afternoon, the system is expected reach West Vancouver Island and bring heavy rain to that region. One hundred to 150 millimetres of rain can be expected by Tuesday morning. Rain will taper off Tuesday afternoon as the system moves eastward.
East Vancouver Island, from Nanoose Bay to Fanny Bay, was placed under a rainfall warning Monday afternoon.
Environment Canada said the same frontal system carrying sub-tropical moisture is set to arrive on the south coast by early Tuesday.
Heavy rain will begin late overnight in the area and persist through early afternoon on Tuesday. Rain will taper off to showers in the afternoon.
A second, weaker system will sweep across the region Tuesday night bringing another round of steady rain. Total rainfall amounts of 50 to 80 mm can be expected by Wednesday morning.
Heavy downpours can cause flash floods and water pooling on roads, the weather agency said. Localized flooding in low-lying areas is possible.