California heat wave temperatures could be 'exceptionally dangerous,' forecasters warn

An intense and potentially record-setting ridge of high pressure continues to build across California and the West, threatening days and perhaps more than a week of a dangerous, life-threatening heat wave.

The worst of the heat will be centered in California’s Central Valley, where as many as 10 days or more of 110-degree heat looms. But just about all of California, stretching into southern Oregon and western Nevada, will swelter for an extended period.

In Southern California, hot conditions are expected to peak by week's end but continue into early next week.

California Heat Alerts / FOX Weather

The high temperatures and low humidity will also create an extended period of elevated to critical fire danger in areas away from the coast, forecasters said.

How hot will it get?

As the system settles in, most areas will see 4 to 8 degrees of warming in coastal and valley areas on Thursday. Valley and inland areas will likely have temperatures that are 10 to 15 degrees above normal by Thursday, according to the National Weather Service. 

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Friday is expected to be the hottest day of the week, with temperatures rising another 2 to 4 degrees, meaning highs of 110 to 115 in interior areas, 100 to 105 in the valleys, 90s along interior coastal areas and 80s at the beaches. Those temperatures are 6 to 12 degrees above normal for the coasts, and 12 to 18 degrees above normal for the valleys and interior areas.

Excessive Heat Warning

An excessive heat warning will be in effect until 6 p.m. Monday for the 5 and 14 freeway corridors, the western San Gabriel Mountains, the Antelope Valley foothills and the Antelope Valley, according to the National Weather Service. Temperatures in the warning area could reach as high as 115 degrees, forecasters said.

An excessive heat warning will take effect at 11 a.m. Wednesday and continue through 6 p.m. Monday in the Santa Clarita Valley, the Santa Monica Mountains Recreational Area, Calabasas, San Fernando Valley and eastern San Gabriel Mountains, where temperatures up to 110 degrees are possible.

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Heat Advisory

The San Gabriel Valley will be under a less severe heat advisory from 11 a.m. Wednesday through 6 p.m. Sunday, but temperatures there are still expected to reach as high as 105. 

The Los Angeles coastal area stretching into downtown is under a heat advisory through 6 p.m. Sunday, with temperatures topping out at 85 to 95 degrees.

In Orange County, a heat advisory will be in effect for the Santa Ana Mountains and foothills and Orange County inland areas from 11 a.m. Friday through 9 p.m. Saturday, with temperatures at or near triple-digit levels.

Elevated Fire Danger

Forecasters said "only minimal cooling" is expected over the weekend, along increasing onshore flow should eventually cool things down along the coasts and slowly move into the valleys. But the high-pressure system is expected to persist, and the heat wave "may push deep into next week," according to the NWS.

"The combination of these very hot temperatures, areas of low humidities and possible sundowner winds will lead to fire weather risks," forecasters said.

Officials are reminding the public to be cautious with any potential fire ignition sources, including fireworks due to the critical fire weather conditions. 

A fire weather watch will be in place from Thursday evening through Friday night in the western Antelope Valley foothills and the 5 Freeway corridor, where forecasters said the hot and dry conditions will be joined by northwest winds potentially gusting from 25 to 40 mph.

Cooling Centers

The city and county of Los Angeles both operate cooling centers for people who need a place to escape the heat. To find a location, call 211 or visit

In the city of LA, cooling centers will be up and running from Wednesday through Monday, 10 a.m. to 9 p.m. at the following locations:

  • Lake View Terrace Recreation Center
  • Mid Valley Senior Citizen Center
  • Fred Roberts Recreation Center
  • Jim Gilliam Recreation Center

City officials also noted that climate stations are available for the homeless on Skid Row, offering cold beverages, shade and seating. The stations are on Towne Street between Fifth and Sixth streets; and at San Pedro Street between Sixth and Seventh streets. Another station will be open by July 16 at Fifth and Maple streets.

The homeless can also visit the ReFresh Spot, 544 Towne Ave. The facility is open 24 hours a day, providing drinking water, restrooms, showers and laundry facilities.

For a list of cooling centers in your county, visit

Safety Tips

Authorities reminded the public to never leave pets or children inside vehicles on days that are even a little warmer than normal, as locked cars can turn into death traps in mere minutes.

Stay Hydrated

  • Drink plenty of fluids. Encourage others to drink plenty of fluids, too.
  • Replace salt and minerals with snacks or a sports drink.

Stay Cool

  • Stay in an air-conditioned place as much as possible.
  • If your home does not have air conditioning, go to your predesignated cool location.
  • Wear lightweight, loose clothing and take cool showers or baths.
  • Limit your outdoor activity. If you must work outdoors, schedule tasks earlier or later in the day.

Prevent Heat Illness

Check on your friends, family, and neighbors. Help them prevent heat illness. Act fast if you notice someone with symptoms. Anyone can develop heat illness. But, people at greater risk are:

  • Older adults
  • Infants, children and pregnant women
  • People with medical conditions
  • Outdoor workers
  • People with limited personal resources
  • People living in places that lack green spaces

FOX Weather and City News Service contributed to this report.