Temperatures are forecast to fall rapidly across the province, with many communities under a flash freeze warning by Environment Canada.
Much of Ontario is expected to be impacted by blowing snow or rapidly falling temperatures throughout Thursday.
Some areas of southwestern and southern Ontario from Windsor to Toronto are expected to see snowfall amounts of five to 15 centimetres, with northwesterly winds gusting to 70 km/h.
While most communities east of Toronto and to the north are expecting freezing temperatures.
“Temperature roller-coasters are common in March, but will be even more of a wild ride this month as we find Ontario right in the middle of the battlefield between remaining Arctic air to the north and the increasing spring warmth that is building to our south,” Global News meteorologist Anthony Farnell said.
The national weather agency warns that ponding water, slush and any falling precipitation will freeze as the temperature drops throughout Thursday.
Icy and slippery conditions are expected to develop as temperatures rapidly fall below freezing.
Environment Canada warns that surfaces such as highways, roads, walkways and parking lots will become icy, slippery and hazardous.
Residents are warned to take extra care when walking or driving in affected areas and be prepared to adjust their driving with changing road conditions.
— with files from Global News’ Kevin Nielsen