On the coldest morning of the winter so far, Durham's Public and Catholic School boards cancelled buses though schools remain open.
The Dufferin-Peel Catholic District School Board has cancelled buses going to elementary schools in Orangeville.
The frigid temperatures also caused problems for transit Thursday morning.
The UP Express was shut down due to the cold and the TTC's Line 3 (Scarborough SRT) was offline because of blowing snow.
Thursday morning was coldest of the entire winter.
Toronto and all of the GTA remain under an Extreme Cold Alert. The temperatures at Pearson at 6 a.m. was minus 22 with a wind chill of minus 36. It's the lowest the mercury has dropped this season.
Sunday's high of 3 degrees is a 25 degree temperature swing from Thursday morning.