The Glass Fire, which began as a 20-acre brush fire near Deer Park, could spread further by winds that are expected throughout the day, Cal Fire said. The fire is 0% contained.
PT, Napa County spokeswoman Janet Upton said. The fire is burning near St. Helena, about 25 miles east of Santa Rosa. Cal Fire said the cause is under investigation.
There are 600 homes and about 1,500 people under a mandatory evacuation order, Upton said, with an additional 1,400 homes and 3,500 people under an evacuation warning, which means they should be prepared to leave if necessary.
Officials are extremely concerned about winds picking up tonight, Upton said. The National Weather Service has the area along with much of Northern California under a Red Flag Warning for fire danger.
St. Helena Hospital was evacuated out of an abundance of caution, the second time the hospital has evacuated this fire season.
Residents are heeding the warnings, said Napa County Sheriff's Office spokesman Henry Wofford.
"We activated the high-low siren on our vehicles because we knew we needed to get people out of there quickly," Wofford said. "When they hear that high-low siren coming from cars as we drove through their neighborhoods they know it's time to evacuate. The motto is, 'If I can hear it, it's time to go.'"
Craig Philpott posted photos and videos to his Twitter account that show the Glass Fire blazing red overnight and the fire's smoke choking the air on Sunday morning.
The scope of Pacific, Gas & Electric's power shut-offs to prevent wildfires in Northern California this weekend has decreased from nearly 100,000 customers expected to be affected, to 65,000 customers.
A press release issued by PG&E Sunday attributes the decrease in numbers to "favorable changes in forecast weather conditions." The utility giant announced the plan late last week due to Red Flag warnings across much of the state.
Power was shut off for 11,000 customers early Sunday morning and the second wave of 54,000 shut-offs is expected to begin at 4 p.m. PT Sunday afternoon, primarily in the Central Sierra Region.
Napa County, where the Glass Fire sparked overnight, is on the list of counties expected to experience shutoffs.
In California, five of the state's top 10 largest fires in recorded history, in terms of acreage, have occurred in 2020 and are still burning.