Cases have exploded in other states as well and governors in some states have instituted virus restrictions like mask mandates and curfews. "But this year we're asking them to limit their travel".
On Friday, it was revealed that President Donald Trump's oldest son, Donald Trump Jr, had tested positive for coronavirus.
The order affects 41 of California's 58 counties, where 94% of the state's population lives.
The latest measures are not as strict as the restrictions imposed between March and May, when all non-essential travel and business were banned. Bars, restaurants and gyms are allowed to open until 22:00, but schools have been closed.
California has put into effect a curfew since Saturday night in an attempt to curb the increase in coronavirus cases. Public health experts have three words for you: "don't do it".
Health officials have warned that the wave of infections could soon overwhelm the healthcare system if people do not follow public health guidance, particularly around not traveling and mingling with other households for the traditional Thanksgiving celebration on Thursday.
"It's not a requirement".
For those considering traveling internationally, the CDC notes that air travel requires waits in security lines and terminals that, even with social distancing implemented, can bring people close together and thereby increase risks of contracting COVID-19.
President-elect Joe Biden has also said he is against imposing a national quarantine and is in favor of states setting their own rules.
The working group said that indoor meetings should be limited for the next two weeks.
The White House has also so far declined to engage with Joe Biden and his incoming administration on policy, as Mr Trump refuses to concede the presidential contest.