Health caution issued as smoke from California wildfires moves into Central Valley

FRESNO, Calif. (KFSN) -- Several wildfires burning in California will affect the air quality in the Central Valley, officials warned on Monday.

The San Joaquin Valley Air Pollution Control District is issuing a health caution for Merced, Madera, Fresno, Kings, and Tulare counties as smoke looms in from surrounding fires, including the Hills Fire in Fresno County.

The Hills Fire broke out this weekend near Highway 33, west of Avenal.

RELATED: Record-breaking heat reported in the Central Valley

The extreme heat and steep terrain have made it difficult for firefighters to contain the 950-acre brush fire, CAL FIRE reported on Monday.

Air officials are urging Central Valley residents to limit the amount of time they spend outside, especially those who have asthma or other respiratory illnesses.