The Glass Fire northwest of St. Helena in Napa County had as of 7 p.m. Sunday grown to more than 2,500 acres, with zero percent containment, and was threatening almost 2,300 structures, Cal Fire said.
No buildings had been destroyed as of 7 p.m. Sunday, and no injuries had yet been reported.
The fire was first reported at about 3:50 a.m. Sunday upon reports of a vegetation fire near the 200 block of North Crystal Springs Road, about four miles northwest of the city of St. Helena in Napa County.
Almost 900 firefighters from numerous local fire departments and Cal Fire were working the fire Sunday night, helped out by numerous firefighting air tankers from throughout the state that were flying as conditions allowed, Cal Fire said.
Firefighting crews overnight will work on perimeter control, defending structures and evacuation planning, Cal Fire said. Hot temperatures and low humidity, combined with erratic winds, figure to make fighting the Glass Fire difficult, firefighters said. Areas on the east side of Silverado Trail from Pickett Road south to Meadowood Lane, and all roads in between, are under mandatory evacuation orders, as are Deer Park Road from Silverado Trail to Howell Mountain Road; the entire community of Deer Park, including St. Helena Hospital, Mund Road and Sanitarium Road; Howell Mountain Road from Deer Park Road to College Avenue; College Avenue from Howell Mountain Road to White Cottage Road; and White Cottage Road from College Avenue to Friesen Drive.
Other areas are under evacuation warning. Cross Walk Church, at 2590 First St. in Napa, has been established as an evacuation center.
In addition to the Glass Fire, fire officials are reporting other fires on the Sonoma and Napa County border, the Shady Fire and the Boysen fire, which are growing toward eastern Santa Rosa.
The North Bay fires have prompted the Bay Area Air Quality Management District to extend a Spare the Air Alert through Monday. Smoke combined with high inland temperatures and vehicle exhaust is expected to cause unhealthy smog accumulation in the Bay Area, mainly in the South and East Bay.
The alert means it is illegal for Bay Area residents and businesses to burn wood or manufactured firelogs in fireplaces, woodstoves and inserts, pellet stoves, outdoor fire pits, or any other wood burning devices.
The National Weather Service has also issued a heat advisory through 7 p.m. Monday and a Red Flag Warning is in effect through 9 p.m. Monday due to dry conditions and gusty winds.