"But really ask yourself -- is it worth it? The infections that come at Thanksgiving will lead to people in the hospital at Christmas," Breed tweeted Monday. "That’s the math. That’s the timeline of this virus. Nobody wants that, so please stay home this Thanksgiving."
The post after came another in which she encouraged the wearing of face masks, limiting interactions and avoiding holiday meals with people outside the household.
She said if one must venture to see family, they should do so outside with masks and observe social distancing rules.
"If you are going to see family, see them outdoors, distances, with masks," she wrote.
Daily coronavirus cases have doubled statewide over the past 10 days. A total of 41 of California's 58 counties are now classified as "purple," the tier of COVID-19 related spread requiring the strictest lockdown guidelines. Just 13 counties were classified "purple" last week.
On Monday, Newsom recently apologized for attending a 12-person dinner party in violation of state guidelines.
Fox Business' Thomas Barrabi contributed to this report.