Dense fog has reduced visibility to near-zero for the third straight day in Metro Vancouver, cancelling flights and creating potentially hazardous travel conditions.

Environment Canada says a fog advisory is in effect for the Greater Vancouver area, as well as the Fraser Valley, Sunshine Coast and eastern Vancouver Island.

At Vancouver International Airport, several flights arriving from other affected communities such as Nanaimo, Comox, Powell River and Campbell River have been cancelled, while many arrivals and departures are delayed.

Environment Canada says the conditions for dense fog and low clouds will dissipate later today as a new frontal system displaces a ridge of high pressure.

In the meantime, the agency is telling motorists to make sure headlights are on and to keep a safe distance from other vehicles.

Dense fog has covered much of Metro Vancouver each morning since Tuesday, when the high pressure system first settled over the region.