Southern California braces for record-breaking heat wave: See the forecast
Weather Forecast for Thursday, March 12
The latest forecast and air quality conditions for the greater Los Angeles area, including beaches, valleys and desert regions.
LOS ANGELES - A significant early-season heat wave is gripping Southern California, pushing temperatures into the 90s across coastal and valley areas and threatening to shatter daily records by three degrees or more, according to the National Weather Service.
With the region still technically in winter, officials are moving quickly to open cooling centers and enforce workplace safety as the mercury climbs 25 degrees above seasonal averages.
What we know:
Meteorologists state that a combination of strong high pressure and offshore flow is driving this spike, with the hottest conditions expected Thursday afternoon.
As a result, the NWS has placed much of the region under a Heat Advisory from 10 a.m. Thursday through 8 p.m. Friday.
In downtown Los Angeles, temperatures are forecasted to hit 93 degrees, while the San Fernando Valley could see 95 degrees.
Cal/OSHA and labor unions like the International Union of Bricklayers & Allied Craftworkers have activated safety protocols, including mandatory shade, electrolyte packets, and frequent breaks, specifically to protect workers who are not yet acclimatized to high heat.
By the numbers:
Temperatures are expected to reach historic highs for mid-March, with many areas seeing temperatures between 20 and 30 degrees above seasonal norms.
Below is a breakdown of the expected highs by county for Thursday, March 12, and Friday, March 13.
Los Angeles County
- Coast: 85° – 94°F
- Valleys/inland: 94° – 99°F (San Fernando Valley)
- Mountains/desert: 80° – 88°F (High Desert)
Orange County
- Coast: 84° – 91°F
- Valleys/inland: 92° – 97°F (Anaheim/Fullerton)
Riverside County
- Valleys/inland: 94° – 98°F (Inland Empire)
- Mountains/desert: 95° – 99°F (Coachella Valley)
San Bernardino County
- Valleys/inland: 93° – 97°F (Inland Empire)
- Mountains/desert: 85° – 90°F (High Desert)
Ventura County
- Coast: 82° – 88°F
- Valleys/inland: 91° – 96°F (Ojai/Simi Valley)
Local perspective:
As temperatures are expected to soar amid a regional heat wave Thursday, the Los Angeles County Department of Public Health is warning people to avoid ocean waters at several beaches due to high bacteria levels.
The affected beach areas are:
- Santa Monica Canyon Creek at Will Rogers State Beach, near Will Rogers Tower 18, 100 yards up and down the coast from the creek;
- Santa Monica Pier, 100 yards up and down the coast from the pier;
- Pico-Kenter storm drain at Santa Monica Beach, near Santa Monica South Tower 20, 100 yards up and down the coast from the storm drain;
- Mothers Beach in Marina del Rey, entire swim area;
- Leo Carrillo State Beach in Malibu, 100 yards up and down the coast from the public restrooms;
- Pulga storm drain at Will Rogers State Beach, near Will Rogers Tower 5, 100 yards up and down the coast from the storm drain;
- Castlerock storm drain at Topanga County Beach, 100 yards up and down the coast from the storm drain;
- Escondido Creek at Escondido State Beach, 100 yards up and down the coast from the creek; and
- Marie Canyon storm drain at Puerco Beach, 100 yards up and down the coast from the storm drain.
Health officials said the warnings were issued after recent water samples showed bacteria levels exceeding state health standards, which could increase the risk of illness.
Meanwhile, warnings were lifted for the following beach areas where recent sample results identified water quality levels within state standards:
- Inner Cabrillo Beach in San Pedro; and
- Herondo Street storm drain in Hermosa Beach, near Hermosa Tower TK.
What we don't know:
While forecasters have high confidence in record-breaking temperatures for official climate sites, the exact duration of the inland "heat dome" remains uncertain, with some models suggesting record heat could persist well into next week.
It is also unclear if the light Santa Ana winds forecasted for Thursday morning will strengthen, which could further exacerbate wildfire risks in dried-out brush areas.
Timeline:
Wednesday: Cal/OSHA issues statewide warning to employers; residents begin heat preparations.
Thursday Morning: Patchy coastal fog clears, followed by light, gusty Santa Ana winds.
Thursday Afternoon: Peak of the heat wave with widespread 90s; Heat Advisory begins at 10 a.m.
Friday: A sea breeze may provide slight cooling for the coast, but the Heat Advisory remains in effect until 8 p.m.
Sunday: Temperatures expected to dip slightly in time for the Academy Awards ceremony.
Monday: Extreme heat shifts north toward San Francisco and Sacramento.
What's next:
While coastal areas may see a minor reprieve by the weekend, high pressure is expected to remain over the region, keeping inland temperatures at near-record levels through early next week.
What you can do:
Sensitive populations should limit outdoor activity as heat risk levels reach "moderate."
Ensure you have access to shade and water, and never leave children or pets in parked vehicles.
Employers are reminded by Cal/OSHA to be especially vigilant with newer employees who may need more time to adapt to the conditions.
The Source: This report is based on information from the National Weather Service. The Associated Press and City News Service contributed.