The parade, in its 45th year, will feature a number of events all weekend including the Grand Parade. It begins Saturday at the CNE grounds and then follows a route along Lake Shore Boulevard West to Parkside Drive.
On Friday police were advising motorists to consider "alternate routes" in the immediate area of the parade and beyond.
"There will be an increase in traffic in the downtown area during this period," police said in a media statement.
At the same time both the TTC and GO Transit will expand service.
Heat, humidity, hydration
People going to the parade were being reminded to prepare for heat and humidity.
Environment Canada's forecast called for sun and heat on Saturday with an expected high of 32 C, while Sunday was expected to see rain with a high of 28 C.
Given the soaring temperatures over the holiday weekend, health officials on Friday were encouraging people "to keep hydrated to beat the heat," as well as to wear comfortable clothing for the parade.
"Light standards along the parade route are marked with an identification number to help people identify the location when reporting a problem to an emergency medical dispatcher," Toronto EMS said in media release.
More uniformed officers
Meanwhile, there will be an increased police presence, part of a plan unveiled last week by Toronto Police Chief Bill Blair who said there would be hundreds more uniformed officers working overtime at the parade.
On Friday, Toronto police spokesperson Mark Pugash said the carnival was not being singled out among the city's many summer festivals.
"The increase in security around the city has been sparked by the increase in violence" in the city in recent weeks, Pugash told CBC News.
"We said that we would be putting pressure on people that we believe were a threat to public safety," he said.
Denise Herrera-Jackson, the carnival's CEO, told CBC's Metro Morning on Friday her organization welcomes the extra police presence.
"We have an excellent relationship with the police," Herrera-Jackson said, noting that police provide security but are also parade participants.
"Their presence is always welcome," she said.