The City of Toronto has issued another special weather statement as the rain is set to change to snow Friday afternoon, creating icy conditions.

This comes after Toronto's medical officer of health issued an extreme cold weather alert Friday morning as temperatures are expected to drop well below freezing. This alert is still in affect "until further notice."

The statement warns of a brief period of freezing rain during the changeover from rain to snow.

"Surfaces such as highways, roads, walkways and parking lots could become icy and slippery. Extra care should be taken when walking or driving in affected areas," the statement said.

Road crews around the city are standing to address the icy conditions.

"City of Toronto crews are taking a very strategic and proactive approach to addressing the potential for flash freezes that could evolve out of rapidly dropping temperatures," said Wynna Brown, a city spokesperson.

"There will be salter trucks that will be strategically positioned across the city and ready to respond as soon as those road conditions get to a temperature that the salt will be effective in reducing slipperiness," Brown told CBC Toronto.

Firefighters deal with a stranded Mercedes on Bayview Avenue south of River Street early Friday morning. (Tony Smyth/CBC)

The statement says the snow is expected to taper off after the cold front, with only a few centimetres expected to fall at most.

The temperature is forecast to drop to –5 C this afternoon, with wind gusts of up to 60 km/h. Friday night's low is forecast to hit –12 C. On Saturday, the forecast high is –11 C.

Geoff Coulson of Environment Canada attributed the quick temperature dip to a "pretty dramatic cold front" from the northwest.

"January can be one of these months where the battle between the milder air masses from the south and the colder ones from the north sort of slug it out," Coulson told CBC Toronto.

"And certainly that's been the case over the last couple of days."

On Thursday, the federal weather agency issued a special weather statement for the city and surrounding areas warning of rain and fog Friday morning, and then the "potential for icy conditions later this morning and afternoon."

Environment Canada warned that morning rain and fog will give way to snow "as temperatures plummet with the passage of a cold front.

"There may also be a brief period of freezing rain during the changeover from rain to snow."

The snow is expected to taper off, with snowfall amounts of only a few centimetres.

Coulson warned that with the frigid temperatures will come the risk of slick roads and sidewalks, as the moisture from the overnight rain and snow melt freezes. After that few centimetres of snow falls, "folks might not be aware of what's underneath them as they are driving or walking," he said.

DVP closed, buses cancelled

The wild weather pattern has led to bus cancellations for:

York Catholic District School Board

York Region District School Board

Durham District School Board

Durham Catholic District School Board

Meanwhile earlier Friday, flooding closed the south end of the Don Valley Parkway for hours overnight, but the lanes reopened before the morning rush got too heavy.

A taxi and a Mercedes were stuck early Friday as flooding closed Bayview south of River Street. (Tony Smyth/CBC)

The city announced the closure of both the north and south lanes shortly after midnight as rain fell on the city. The northbound lanes re-opened around 5:30 a.m., while the southbound lanes reopened shortly before 6:30 a.m.

The nearby Bayview extension was closed south of Dundas Street East, as firefighters helped motorists stranded in deep pools of water overnight. Shortly after 7:30 a.m., the city tweeted that Bayview had reopened.

Flood warning cancelled

The Toronto and Region Conservation Authority had issued a flood warning, noting that parts of the Greater Toronto Area received approximately 10 mm of rain Thursday evening.

But before 7 a.m. Friday, the TRCA issued another statement, stating that water levels in the "majority" of its rivers and streams had peaked "and are now receding."

However, those levels remain "higher than usual" and riverbanks are slippery, the statement said.

"Ponding may still occur in low-lying areas. The combination of slippery and unstable banks, cold water temperature, and the potential for ice jamming could create hazardous conditions close to any river, stream or other water bodies. All shorelines, rivers and streams within the GTA should be considered hazardous."

The statement advised residents to "exercise caution around all bodies of water."