Los Angeles faces scorching 119° as heat wave affects 31 million in 3 states

A series of scorching, triple-digit temperatures across Southern California led to warnings from public health officials and some schools closing earlier Friday as part of a larger heat wave gripping an area of the southwestern U.S. spanning three states.

More than 31 million people in California, Nevada and Arizona were under an excessive heat warning issued by forecasters as temperatures soared Friday, according to the National Weather Service . In Southern California, the advisory is expected to last until Monday night after forecasters extended an earlier warning that was supposed to end Friday.

Residents of the region faced scorching temperatures well into the triple digits — from 119 degrees in Woodland Hills to 115 degrees in Riverside — as air quality regulators warned of unhealthy breathing conditions tied to the heat and some Los Angeles area schools ended classes early due to the weather and power outages . In Pasadena, rolling outages were issued after the extreme heat caused an equipment failure .

And a number of cities saw record-breaking temperatures Friday.

The excessive heat warning extends from the southernmost end of Central California all the way across Southern California to the U.S.-Mexico border. The National Weather Service has warned of "dangerously hot conditions." Other parts of California further north are under a less severe heat advisory that's also warning of warmer than usual weather.

Forecasters have issued a red flag warning in parts of LA, Ventura and Santa Barbara counties due to the risk of wildfires potentially sparking and spreading quickly due to especially dry, hot conditions — telling people in high-risk areas to be ready to evacuate. In San Bernardino County, a wildfire grew to more than 1,100 acres after starting the day before and triggering evacuation warnings.

On Friday, with the sweltering heat expected to continue into the weekend, public health officials in LA County spoke out.

"As temperatures are forecast to continue to soar into the triple digits, the Los Angeles County Department of Public Health urges residents to take precautions to avoid heat-related illnesses such as heat exhaustion, heat stroke and heat cramps," said Dr. Anish Mahajan, chief deputy director of the health department.

Populations who are especially vulnerable to the extreme heat include those with chronic health conditions, children, pregnant women, elderly people as well as athletes and workers who spend long stretches of time outside, according to Mahajan.

"Workers who are working outside are at really high risk of heat-related illnesses," Mahajan said, explaining that employers are legally required to provide workers at outdoor job sites with shade when temperatures exceed 80 degrees.

In LA's Los Feliz neighborhood, as the temperature reached 103 degrees Thursday, firefighters spent nearly six hours working to rescue a construction worker trapped inside an 8-foot deep trench , surrounded by soil reaching up to his shoulders.

Two of the firefighters were treated for heat exhaustion, with one of them taken to a hospital, while the worker was left in serious condition and also had to be rushed to a hospital after being trapped underground in the baking heat for hours.

Meanwhile, for the broader population, air quality has become a real point of concern due to the heat wave.

Ozone pollution — specifically "ground-level ozone" which develops when gases from pollution interact with sunlight and form ozone smog — is currently at concerning levels across Orange, Los Angeles, San Bernardino and Riverside counties, according to the South Coast Air Quality Management District. The regulator issued an ozone advisory that will remain in effect until Monday at 8 p.m.

People are being told to stay indoors, avoid physical activity and conserve energy due to the poor air quality. Health risks such as shortness of breath, wheezing and coughing are a concern as well as more serious health effects over the long run, according to the American Lung Association .

"Many areas in the United States produce enough ozone during the summer months to cause health problems that can be felt right away," the organization says. "Long-term ozone exposure is associated with increased respiratory illnesses, metabolic disorders, nervous system issues, reproductive issues... cancer and also increased cardiovascular mortality, which is the main driver of total mortality."