LOS ANGELES — A wildfire in a wilderness area of central California exploded in size as dry, hot weather Thursday raised 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, ripping through grasslands after breaking out Wednesday in southeastern San Luis Obispo County. It swiftly grew to more than 82 square miles (212 square kilometers). It was just 10% contained by Thursday evening.

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 45 miles (72 kilometers) east of Santa Maria. The region about 125 miles (200 kilometers) northwest of Los Angeles contains vast grasslands that draw visitors in the spring to see its wildflowers.

Part of Route 166 East was closed Thursday, and there was “no estimate for re-opening,” California Department of Transportation, known as Caltrans, said on social media.

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 40 mph (64 kph) later in the day Thursday, posing new challenges for firefighters working in 95-degree F heat (35 C).

Dozens of smaller wildfires were burning across the state.

Southern California’s Wolf Fire reached 55% containment Thursday after charring more than 3.7 square miles (9.5 square kilometers) of dry brush since breaking out June 29 in Riverside County east of Los Angeles.