A wildfire in a wilderness area of central California has exploded in size as dry, hot weather raise the fire risk for large portions of the state ahead of the July Fourth holiday.

The Madre Fire became California’s largest blaze so far this year on Thursday, ripping through grasslands after breaking out Wednesday in southeastern San Luis Obispo County. It swiftly grew to more than 140sq km. There was just five per cent containment.

Evacuation orders and warnings were issued for tiny communities near State Route 166 as flames moved through hilly terrain toward the Carrizo Plain National Monument, about 70km east of Santa Maria. The region about 200km northwest of Los Angeles contains vast grasslands that draw visitors in the spring to see its wildflowers.

The fire was pushed by summer gusts that typically increase as the sun starts going down, said meteorologist Ryan Kittell with the National Weather Service.

“The winds are pretty light during the day, but they do pick up pretty substantially in the afternoon and evening hours,” Kittell said.

He said gusts could reach 65km/h later in the day Thursday, posing new challenges for firefighters working in 35C heat.

Dozens of smaller wildfires were burning across the state.

Southern California’s Wolf Fire reached 55 per cent containment Thursday after charring more than 9.5sq km of dry brush since breaking out Sunday in Riverside County east of Los Angeles.

Source: AAP