Dense fog in low-lying areas of Metro Vancouver has prompted a warning from Environment Canada.

"If travelling, be prepared for areas of near zero visibility," said the fog advisory issued Wednesday morning.

The fog is forecast to persist through the morning, and break up in the afternoon, but not clear out entirely.

"What we are looking at is an upper ridge of high pressure which is keeping the situation quite stable," said Environment Canada meteorologist David Wray.

Active pass fog

A BC Ferries passenger takes a photo through the fog in Active Pass. (Carrie McLaren)

Harbour Air Seaplanes grounded four flights Monday morning, and posted travel alerts on its website for flights to South Vancouver, Victoria Harbour, Nanaimo, Comox and the Gulf Islands.

The B.C. government's E-Comm service warned drivers to take extra care on the roads.

"Slow down and remember low beams are more effective," tweeted E-Comm.

Starting to lift

Mid-morning, the fog began to lift and separate in Vancouver. (Claire Martin)

The fog is only about 200 or 300 metres thick, so higher elevations saw sunshine Wednesday, said Environment Canada.

Above the clouds

In West Vancouver, it was sunny above the low-lying fog. (Royal Canadian Marine Search and Rescue)

With files from Terry Donnelly