Rain is in the forecast all over the Island Wednesday night, and Environment Canada issued warnings for the east and west regions.
The weather service says an intense frontal system is moving through the south coast and East Vancouver Island near Bowser is expected to get 80 to 100 millimetres of rain by Thursday morning.
Near Courtenay, the amount is expected to be 50 mm before the rainfall eases Thursday morning.
For West Vancouver Island, rain is expected to intensify significantly Wednesday night
with accumulations of 100 mm expected.
Areas around Zeballos and Tahsis may see 120 mm of rain before it eases Thursday morning.
Environment Canada says heavy downpours can cause flash floods and water pooling on roads., and there is a threat of localized flooding in low-lying areas.