The new rules took effect at 11:59 pm on Sunday for a large swath of the Central Valley and all of Southern California. The rules were triggered when available capacity in the region's intensive care units fell below 15%.
The new order applies to the following counties: Calaveras, Fresno, Kern, Kings, Madera, Mariposa, Merced, San Benito, San Joaquin, Stanislaus, Tulare, Tuolumne.
RELATED: 'Vast majority' of California under stay-at-home order as ICU capacity reaches critical levels, Newsom says
As of Monday, the ICU capacity in the San Joaquin Valley was 6.3%.
"The bottom line is if we don't act now our hospital system will be overwhelmed," Newsom said. "This is the most challenging moment since the beginning of this pandemic."
Business owners across Central California were rushing to prepare for the new restrictions while others closed entirely for at least the next three weeks.
The earliest the order could possibly be lifted is December 27. Regions will be eligible to exit from the order on Dec. 28 if ICU capacity projections for the following month are above or equal to 15%.
While the state is mainly leaving it to local leaders for the order to be implemented, Newsom said on Thursday that there will be consequences for the counties that fail to cooperate.
Bars, wineries, nail salons, hair salons and barbershops, and other personal care services need to close. Private gatherings of any size will not be allowed.
Schools that were given a waiver to reopen will be allowed to stay open.
Restaurants will have to remove both indoor and outdoor dining and move back to take-out and delivery only.
RELATED: What's next for Valley restaurants during looming stay-home order
All retail stores will be allowed to stay open at 20% capacity.
All non-essential travel is "temporarily restricted statewide," regardless of what zone you live in. Hotels and motels are now restricted to only guests traveling for an "essential" reason.
For more news coverage on the coronavirus and COVID-19 go to ABC30.com/coronavirus