California is bringing back a statewide indoor mask mandate. Gov. Gavin Newsom's administration announced the new mandate will start Wednesday and last until Jan. 15. The order comes as the per capita rate of new coronavirus cases in California has jumped 47% in the past two weeks, according to state health officials.

California also is tightening existing testing requirements by requiring unvaccinated people attending indoor events of 1,000 people or more to have a negative test within one or two days, depending on the type of test. The state also is recommending travelers who visit or return to California to get tested within five days of their arrival.

State Health and Human Services Secretary Dr. Mark Ghaly said the state will reimplement an indoor mask requirement, regardless of vaccination status,

Ghaly said the recent rise of the omicron variant of the virus and the increase in cases statewide since Thanksgiving has led to concern over a possible surge in cases similar to last winter's surge.

"We know that we are entering into a pretty hard time and we are starting to see some of these numbers go up in some communities pretty quickly," Ghaly said. 

Most of the state's most populous areas, including the Bay Area, have had indoor mask requirements for several weeks since the delta variant first led to a spike in COVID-19 cases, hospitalizations and deaths in August.

Ghaly said Monday that the new mask mandate will affect roughly half of the state's population who live in an area that does not currently require masks in indoor public spaces, regardless of vaccination status.

Individual venues, stores and other indoor public spaces will continue to be responsible for enforcing the mask rules, according to Ghaly, who said he hopes that people who enter indoor public spaces over the next month do so with the expectation that they will be required to wear a mask or other face covering.

The state is not planning to reimplement restrictions on certain businesses like it did prior to June 15, when the state's color-coded reopening system was lifted.