Environment Canada now says all of the Greater Toronto Area and Hamilton will experience freezing rain early Monday morning.
Areas including Barrie, Orillia, Waterloo Region, Wellington County, Peterborough and the Kawartha Lakes are also covered by the warning.
The freezing rain will fall for a short period because changing over to rain as temperatures rise.
10-15 millimetres of rain is expected.
The high for Monday is forecasted to be 11 C.
Environment Canada Meteorologist Mitch Meredith tells NEWSTALK1010 that if the mercury reaches 11 degrees, it will break a record of 9.8 degrees set in 1982.
The OPP reports that GTA-area highways were slippery at 6 a.m. Monday morning and warned motorists to drive according to conditions.