People in the London region should prepare themselves for a blasting of snow followed by several days in the deep freeze.
Environment Canada has issued a winter weather travel advisory for London, Middlesex County, Oxford County, and western Elgin County warning between 5 to 10 centimetres of snow could fall Friday night.
A wind warning was also issued Friday for eastern Elgin and Norfolk Counties, with the potential for winds up to 100 kilometres per hour.
The snow, which will be heavy at times, is expected to arrive in the area in time for the tail-end of the afternoon commute.
"Motorists should expect hazardous winter driving conditions and adjust travel plans accordingly. Avoid travel if possible," the national weather agency said in a statement.
The snow will change over to periods of rain around midnight as the temperature rises above freezing. The rain will then transition back to snow Saturday, dropping another 2 centimetres before tapering off late in the day.
Saturday is also when an arctic air mass will sweep across the province, plunging temperatures below seasonal and giving southwestern Ontario residents their first taste of frigid conditions this winter. The region saw an unseasonably warm December and start to January. The average daytime high for this time of year is -2 C. Starting Sunday and continuing into next week the daytime high will be around -10 C.
The cold spell is expected to last until next Thursday.