It applies to "purple tier counties", which includes 41 of California's 58 counties.
Those counties are now classified within the state's "purple tier", which includes communities where more than 8 percent of COVID tests over the past week have come back positive.
The month-long curfew could be extended if rapidly worsening trends don't improve.
"In response to much social uncertainty and numerous inquiries, I wanted to clarify the position of the Sacramento Sheriff's Office relative to existing health orders, as well as any potential impending orders at the County or State level".
The curfew impacts "non-essential work and gatherings" and was specifically developed to stop social events where drinking could impair judgement regarding COVID-19 precautions. A business that is not deemed essential must also close between the hours of 10 p.m. and 5 a.m.
Restaurants will be allowed to offer take-out after that time.
On Nov. 19, Rep. Tom McClintock (R-Calif.) said Newsom was exercising his free will when he attended the party. "It is crucial that we act to decrease transmission and slow hospitalizations before the death count surges".
© David Livingston/Getty Gov. Gavin Newsom announced the curfew that will run from 10 p.m. until 5 a.m. every night. The state will reassess data continuously and move more counties back into a more restrictive tier, if necessary.
Only a week ago Governor Newsom "pulled the brake" on California's reopening, including issuing a travel advisory.
The El Dorado County Sheriff's Office will not be enforcing the state issued curfew order, department officials announced Thursday evening. Those who enter California from another state or country are urged to self-quarantine for 14 days after arrival. "Throughout the pandemic, the Orange County Sheriff's Department has taken an education-first approach with regard to the public health orders", said Barnes in the statement.
The tightening of restrictions comes as California health officials say the state has recorded another record-breaking number in daily coronavirus cases.
Cailey Rizzo is a contributing writer for Travel + Leisure, now based in Brooklyn.