A rainfall warning has been issued by Environment Canada.
Between 40 to 60 millimetres of rain is expected fall Wednesday into Thursday.
According to the government weather agency, a slow moving Pacific frontal system is moving across the BC south coast, causing the storm.
The rain will begin near midday on Wednesday, Nov. 12, and gradually intensify through the day.
Heavy rain is expected to continue through the night into Thursday, and then ease Thursday night.
Water will likely pool on roads and in low-lying areas. The agency is also warning that landslides may occur in vulnerable areas such as steep slopes, deforested areas or recent burn scars.
Wind will be around 20km/h at around midnight and then 30 km/h, gusting to 50, on Thursday night.