One notable change from the January 2021 shutdown is the province will not issue a stay-at-home order this time.
Some outdoor activities will be allowed such as golf, but team sports will not be permitted.
This will be the third full provincial closure (of varying severity) since the beginning of the COVID-19 pandemic in March 2020.
Premier Doug Ford said the rapidly spreading coronavirus variants are to blame. "This is a new pandemic; we're fighting a new enemy". "It's spreading far more quickly than it was before and we can not vaccinate quickly enough to break this third wave, this is the challenge of the new variants".
Indoor social gatherings are prohibited and outdoor gatherings will be limited to five people.
"If you live alone, you can have close contact with only one other household", the province says.
Take-out and delivery options will still be available.
The rules are slightly more lax for religious, wedding and funeral services in Ontario, however, with indoor events permitted to host up to 15 per cent of a room's capacity.
Two-thirds of the province's public health units are now under what the government calls lockdown (grey zone) or control (red zone) restrictions. I'm the one who has to make the tough decisions.
"This is a top priority", said Ford.
"Effective, Saturday, April 3 at 12:01 a.m. [4:01 a.m. GMT], Ontario will pull the emergency brake for the entire province", Ford told reporters.
Ontario Health Minister Christine Elliott, meanwhile, said that the dosing interval could be reduced if incoming supply levels allow. We saw what happened in the last holiday season, it took off.
"The current measures and framework are not working to contain the spread of this virus", reads the letter in part.
"My friends, we're facing a very, very serious situation", said Ford.
The letter says doctors are seeing younger patients on ventilators, many of whom are parents of school-aged children.
Ontario's science advisers confirm the troubling trend, saying on Thursday that strict, stay-at-home orders are needed to control the third wave of COVID-19 in the province.
New modelling also shows Ontario could have up to 6,000 new cases a day by the end of April due to the new variants of the virus.
A source with knowledge of the restrictions discussed at an hours-long cabinet meeting Wednesday night says the final details of the new measures will be worked out this morning. "The public health measures fall short of what many experts are calling for". "The risk of death is 1.5 times higher".
Premier Doug Ford announced the move this afternoon resulting from a surge in COVID-19 cases and intensive care admissions across the province.
Outdoor fitness classes also briefly resumed in regions under the grey zone.
"Ontario, Canada, we're getting a little bit fed up".
In-person shopping is restricted to 50 per cent capacity for supermarkets, grocery stores, convenience stores, indoor farmers' markets, stores that primarily sell food, and pharmacies. Public health and infectious disease officials are warning that variants of concern are generating more rapid and widespread transmission and increasing risk.
At this time, schools will remain open.