York Region will transition back into a modified stage 2 effective Monday at 12:01am for 28 days.
Premier Doug Ford made the announcement saying "by all accounts" the situation in York region is headed in the wrong direction.
Cases per 100,000 are now at 39, well above the provincial average, Ford says.
712 new cases were reported in Ontario today.
York will join Toronto, Peel and Ottawa in the phase-two situation which bans indoor dining, and closes cinemas, gyms and casinos for 28 days.