Forecasters are predicting a break in the heat wave that has contributed to the deaths of more than 100 people in California.
Searing temperatures and unusually high humidity have plagued the state for 12 days.
Weather experts said they expected cooler temperatures Friday. In the hardest-hit Central Valley, aid workers went door-to-door to make sure elderly residents survived the intense temperatures. Hospitals and morgues are strained for resources.
Cattle are dying, as well, leaving dairy farmers with reduced output. The New York Times newspaper reports California state officials have waived regulations on transporting and disposing of dead animals, to help farmers deal with a backlog of corpses.
The increased demand on the state's electrical grid has caused power outages at a time when air conditioning is most important.
The strain could grow in coming days, as wildfires approach transmission lines in northern California that transport energy from the Pacific Northwest. The transmission lines serve millions of homes in the state
Some information for this report was provided by AP.