Environment Canada has issued a rainfall warning for Metro Vancouver, the Fraser Valley and the North Shore — with upwards of 150 millimetres of rain expected.
A plume of tropical moisture will bring prolonged periods of rain, heavy at times, to Vancouver, North and West Vancouver, Coquitlam and the Fraser Valley over the next two to three days.
The South Coast should expect the downpours to continue until Thursday, and then taper off as the system moves inland.
Environment Canada said localized flooding in low-lying areas is possible.
A system that moved through downtown Vancouver Sunday dropped 25 millimetres of rain within a three-hour period.
CBC meteorologist Johanna Wagstaffe said the active pattern of heavy rain, coupled with forecasted milder temperatures, also brings a heightened risk for avalanches.
"Anytime we have a big snow dump like we just did this weekend followed by an atmospheric river, that is a recipe for avalanche risk," Wagstaffe said.