Environment Canada says the thick fog that descended on southern Ontario early Thursday is expected to dissipate by late morning.
The weather agency advised of near-zero visibility due to fog across several regions in southern Ontario, stretching from London across the Toronto area to Kingston, and as far north as Barrie, Muskoka, and cottage country.
The agency said visibility may be significantly and suddenly reduced to near zero.
“Travel is expected to be hazardous due to reduced visibility,” Environment Canada said.
It added that if visibility is reduced while driving too slow down, watch for tail lights ahead and be prepared to stop suddenly.
According to Anthony Farnell, Chief Meteorologist for Global News, the fog rolled in off of Lake Ontario on Wednesday afternoon because “on a sunny day, land heats up quicker than water.”
“The air over land also warms and rises, which can draw the cool damp and very dense lake air inland, but only in the lowest level of the atmosphere,” Farnell said.