The Madre Fire ignited Wednesday afternoon in San Luis Obispo County and has since grown to more than 52,000 acres, according to Cal Fire.

The fire sparked in the Los Padres National Forest in San Luis Obispo County and was growing exponentially, officials warned. The area is mostly uninhabited.

California’s largest wildfire of the year grew to an estimated 70,801 acres Friday, producing smoke that has affected millions of residents across the southern part of the state. The Madre Fire in San Luis Obispo County erupted early Wednesday afternoon near the small town of New Cuyama along Highway 166 on the Carrizo Plain,