Drivers are being urged to take it slow during the afternoon commute on Monday, with scattered showers expected to fall in many parts of the Greater Toronto Area beginning at about 1 p.m.
Geoff Coulson, a Toronto-based meteorologist for Environment Canada, said the rain will become more intense and widespread after 5 p.m.
"We're not used to driving on slick roads," Coulson said Monday. "Driving more slowly when commuting home is probably a good idea."
Coulson said a low pressure system coming from the U.S. midwest is bringing the moisture to the GTA.
The system is also bringing cooler weather, a marked change from the warm temperatures that enveloped the city on the weekend and earlier this month.
The wet weather won't end on Monday: Environment Canada said the forecast calls for a 60 per cent chance of rain on Tuesday, with between two to five millimetres expected, and a 40 per cent chance of rain on Wednesday, with two to three millimetres expected. Rain is also anticipated on Friday and Saturday.
Coulson said Toronto residents should start thinking about wearing warmer clothes.
"We are getting weather that is more like fall. We are starting to see a shift in the weather pattern," he said.
The high for Monday is forecast to be 20 C, with a low of 13 C.
Meanwhile on Tuesday, the high is expected to be 15 C, with a low of 9 C. And Wednesday, the high is forecast to be 12 C, with a low of 6.
The normal high for this time of year is about 12 C and the normal low is 4 C.
Coulson said the rain is coming after a drier than normal September, when just 29.8 millimetres of precipitation fell. The normal amount of precipitation for September is 74.5 millimetres.
October has also been drier than normal. 42 millimetres of rain have fallen so far, though rain this week could bring total precipitation amounts for Toronto closer to normal for this month, he said.
The normal amount of precipitation for October is 61 millimetres.