Southern Manitoba is shrouded in heavy fog for the third-consecutive day — so thick in places there is zero visibility on some highways.

As a result, the Borderland School Division, which serves the Altona region, has canceled buses and classes for the day.

Division transportation coordinator Todd Nichols said the problem is most of the students come from rural areas and officials don't want to risk the highway travel.

Pedestrians make their way across Portage Avenue on Feb. 3, with the downtown skyline cloaked in fog. (Darren Bernhardt/CBC)

With fog this thick, drivers wouldn't see buses stopped on the highways to pick up students.

"It wasn't as bad out here in the rural yesterday. You could see one, maybe two, hydro poles in most of the areas yesterday," Nichols said.

"Right now? I just had my mechanic come in he is saying [he could see] one, maybe two, yellow lines [on the highway]."

The fog is the result of mild temperatures, melting snow, and a lack of wind leaving all that moisture in the air, according to Environment Canada.

On Wednesday, the damp air was also blamed for sparking a fire on a hydro pole in Winnipeg. Electricity in the power lines arcs across the insulator and sets the pole top on fire.

Hydro spokesperson Scott Powell said it can be quite common in foggy weather to have such fires.

Little improvement in the conditions is expected Friday until the late morning, the weather agency said.

The fog will likely return Saturday morning, however, as above-normal temperatures persist.