Environment Canada says strong winds of up to 90 km/h and significant rainfall are expected late Saturday afternoon over B.C.'s Lower Mainland as a large early-season storm moves in.

The winds were already blowing over sections of the Sunshine Coast and on the east side of Vancouver Island Saturday morning.

Vancouver rainfall street flooding

A man uses a rake to clear debris from a storm drain grate at the side of a flooded East Vancouver street Saturday afternoon. (CBC)

"These gusty southerly winds are expected to spread to Vancouver and portions of the Fraser Valley just as the front crosses the Lower Mainland late this afternoon and evening," Environment Canada's Saturday morning bulletin said.

It says the winds are potentially damaging so residents should monitor conditions and watch for updates.

The storm, which is full of sub-tropics moisture, is also bringing heavy rain to several areas in and around Metro Vancouver.

Howe Sound, the North Shore, and areas extending east to Coquitlam and the Fraser Valley north of the Fraser River can expect 40 to 60 mm of rain Saturday.

Early season storm - Environment Canada

A storm front bringing strong winds and heavy rainfall moves in towards British Columbia's South Coast, shown at noon PT Saturday. Environment Canada says the early season storm is only one in a series of storms that will impact the B.C. coast this weekend. Another storm is poised to strike the South Coast early Sunday evening. (Environment Canada)

As of 11 a.m. PT Saturday, Environment Canada said the rain was expected to taper off into a few showers in the evening.

It also warned that a second low pressure system with the potential for even stronger winds is expected to hit Sunday night, but the precise track of the second storm is uncertain at this time.

"Forecasts and warnings will be updated as the second low's track becomes more certain," Environment Canada said.

With files from the CBC's Johanna Wagstaffe