Fire crews responded Monday afternoon to a vegetation fire that broke out in an area southwest of Mount Diablo, officials said.

It was unclear initially exactly where the fire began and whether any homes or commercial buildings were threatened. Fire crews from the Contra Costa Fire Protection District and Cal Fire had been called to the blaze.

The first reports of the fire came in about noon.

The fire came amid relatively mild weather. Temperatures were expected to peak at 84 degrees at Mount Diablo on Monday, according to the National Weather Service. Winds were blowing about 5 mph.

The smoke added to air that was not the cleanest already on Monday. The Bay Area Air District already had extended an air quality advisory for wildfire smoke that had been issued originally on Sunday. The coastal and central Bay Area was expected to have moderately healthy air quality, while the rest of the region’s air was forecast to be good.

About the same time, crews also responded to a wildfire in Rodeo at Clayes Court and Stirling Drive. Cal Fire said in an update around 1:45 p.m. that the Rodeo Fire had grown to 62 acres.

This is a developing story. Please check back for updates.

Originally Published: June 23, 2025 at 12:45 PM PDT