Hardest hit is Nanaimo, where 2,393 customers are without power after a tree crashed onto power lines in the 600 block of Wakesiah Avenue.
The city’s aquatic centre is closed for now because of the power cut.
A tree across the lines also knocked out power for 1,803 customers in Parksville.
A few hundred customers were without power in Qualicum Beach because of fallen electrical wires and a few dozen in Courtenay due to trees across wires.
Islanders have been filling sandbags and bracing for ongoing downpours. A social media post showed the impact in Ucluelet, where water in storm drains is bubbling onto the street.
Environment Canada posted a wind warning for east Vancouver Island from Nanoose Bay to Campbell River, forecasting winds of 70 km/h gusting to 90 km/h. Winds are expected to ease later this morning.
Mainroad, the highway maintenance contractor for the central Island, is urging drivers to slow down as the rain comes down, reducing visibility.