California Issues Sweeping Heat Advisory for Over 5 Million Residents

Dangerous temperatures expected to grip Southern California for 34 hours, raising risk of heat-related illnesses.

Published on Mar. 10, 2026

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California officials have issued a heat advisory affecting more than 5 million residents in Southern California, warning of dangerous temperatures reaching the upper 90s and potentially breaking records. The 34-hour advisory covers San Diego, Orange, Riverside, San Bernardino, Los Angeles and Ventura counties, urging people to stay indoors during the hottest parts of the day to avoid heat-related illnesses.

Why it matters

This unusually early-season heat event is highly anomalous for March, with temperatures forecast to be 20-25 degrees above average. The extreme heat poses a serious risk to vulnerable populations like young children, older adults, and those without access to air conditioning or who must work outdoors.

The details

The National Weather Service is warning that temperatures could climb to 93-98 degrees in inland areas and 88-92 degrees along the coast. Several daily and monthly temperature records are at risk of being broken. Forecasters say the heat will not subside after Friday, with elevated temperatures expected to linger into the weekend and beyond.

  • The heat advisory will be in effect from 10 a.m. Thursday to 8 p.m. Friday.
  • Temperatures are forecast to remain above average across California and the U.S. West through at least March 24.

The players

National Weather Service

The federal agency that issues weather forecasts and warnings for the United States.

Sebastian Westerink

A meteorologist with the National Weather Service who spoke to Newsweek about the unusual heat event.

Jeff Berardelli

The chief meteorologist at WFLA-TV who posted on X about the potential for record-breaking temperatures in Los Angeles.

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What they’re saying

“This is very anomalous heat for the month of March. We typically don't see upper 90s or 100s until June.”

— Sebastian Westerink, Meteorologist (Newsweek)

“Pretty amazing in SoCal. Downtown LA may hit 100° on Friday! That's crazy. Checked the data. The earliest 100 was April 4th. So IF this happens, it would be 3 full weeks ahead of the earliest 100. Also obviously the hottest March temp on record in LA as well (97 is the monthly record). Should be noted that National Blend of Models (NBM) experimental has 99-100 there, so the possibility is not pie in the sky.”

— Jeff Berardelli, Chief Meteorologist (X)

What’s next

The Los Angeles/Oxnard office of the National Weather Service noted a 'high risk for heat illness' and said additional advisories or even extreme heat warnings may follow as above-normal temperatures persist into next week.

The takeaway

This early-season heat wave in California is highly unusual and poses a serious threat to public health, especially for vulnerable populations. It highlights the growing challenge of extreme weather events driven by climate change, and the need for communities to be prepared with robust heat response plans.