Residents were directed to be ready to flee in an area from County Road 110 to Duncan Springs, southwest of Hopland. Deputies earlier issued an evacuation warning for downtown Hopland.
Highway 101 was closed from Burke Hill Road in the north to the junction with state Highway 175 in the south, Caltrans said.
Three night-flying helicopters were ordered to the area to help with the firefight, Cal Fire said.
The Feliz Fire was first reported at 40 acres in the area of Feliz Creek Road about 3:40 p.m. It was 550 acres and 5% contained as of 7:55 p.m., according to Cal Fire.
A temporary evacuation point was established for residents displaced by the fire at the Mendocino County Office of Education at 2240 Old River Road in Ukiah, Mendocino County said on social media.
Residents with pets displaced by the fire were directed to take them to the Mendocino County Animal Shelter, 298 Plant Road, Ukiah. A shelter for livestock and other large animals was established at Redwood Empire Fairgrounds, 1055 N. State St., Ukiah.
The cause of the fire was under investigation.
Sonoma County issues health advisory due to poor air quality caused by the Feliz Fire
The Sonoma County Health Officer issued a health advisory for residents as the Feliz Fire affects air quality in the area.
"Areas of northern Sonoma County may experience 'Unhealthy for Sensitive Groups' or 'Unhealthy' air quality caused by the wildfire event in Mendocino County near Hopland. Certain people may experience adverse health effects from the smoke over Sonoma County and across the region. High temperatures can worsen effects of high Air Quality Index (AQI) events," officials said in a press release.
Residents are encouraged to monitor the air quality in their area as it can fluctuate in different parts of the county "due to a number of factors."
MAP: Track wildfires across California
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