Ontario reported 125 new COVID-19 infections on Tuesday and four new deaths, the highest daily count of infections in more than one month.
The province last reported a higher number on July 30, when 134 infections were found.
Ontario reported 99 new cases on Monday, 81 on Sunday, 106 on Saturday and 92 on Friday.
It is the highest count of cases since Toronto and Peel Region were allowed to join most of Ontario in Stage 3 of reopening, which allowed activities such as indoor dining, attending fitness centres and cinemas to resume.
Health Minister Christine Elliott said the increase was due to a series of "localized increases with 17 cases in Peel, 27 in Toronto and 28 in Windsor-Essex."
"Today, 27 of 34 public health units are still reporting five or fewer cases, with 16 of them reporting no new cases," she said on Twitter.
She said provincial labs processed 23,000 tests in the last 24 hours, down from 25,500 on Monday.
Sixteen thousand test specimens remained under investigation on Tuesday.
Tuesday's results produced a positivity rate of 0.54 per cent.
Ninety Ontario residents recovered from infection in the past 24 hours, meaning the number of remaining active cases in the province rose by 31 to 951.
There have now been 40,870 lab-confirmed cases of novel coronavirus infection in Ontario, with 2,793 deaths and 37,126 recoveries since January 25 when Ontario's index case was detected.
Sixty per cent of new infections detected were in people aged 39 or younger.
There are now 41 people being treated for COVID-19 symptoms in hospitals across Ontario.
Of those, 15 are in intensive care, with eleven of them breathing with the help of a ventilator.
