California officials have issued a sweeping heat advisory affecting more than 5 million residents, warning that dangerous temperatures will grip coastal and inland communities from Thursday morning through Friday evening.
The National Weather Service is urging people to stay indoors during the hottest parts of the day as an unusually early-season heat event pushes temperatures into the 90s across much of Southern California. Forecasters say the 34‑hour advisory, which covers San Diego, Orange, Riverside, San Bernardino, Los Angeles and Ventura counties, could lead to heat-related illnesses, especially for people without access to air conditioning or those who must spend time outdoors.
The NWS cautioned that the warmth will not end Friday night; elevated temperatures are expected to linger into the weekend and beyond.
“This is very anomalous heat for the month of March,” NWS meteorologist Sebastian Westerink told Newsweek. “We typically don’t see upper 90s or 100s until June.”
The average high temperature for the area during this time of year is 73 degrees. Several records are at risk of being broken, according to data from the NWS Weather Prediction Center.
In San Diego, Orange County and the Inland Empire, temperatures could climb to 93 to 98 degrees in inland zones and into the upper 80s to lower 90s along the coast, according to the NWS office in San Diego. A nearly identical timeline and temperature range are forecast for Ventura and Los Angeles counties, where widespread readings of 90 to 100 degrees are expected.
“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,” WFLA-TV chief meteorologist Jeff Berardelli posted on X. “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.”
Heat advisories in both regions will be in effect from 10 a.m. Thursday to 8 p.m. Friday.
Forecasters warn that vulnerable populations, including young children, older adults, people without home cooling systems, and those who work or exercise outside, face a higher risk of heat exhaustion or heat stroke.
The Los Angeles/Oxnard office 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.
Residents in the affected areas were urged to drink plenty of water, stay in air‑conditioned spaces when possible, avoid direct sun exposure, check on neighbors, family members, and the elderly, limit strenuous outdoor activity to early morning or evening, and wear lightweight, loose‑fitting clothing.
Looking further ahead, there’s a high chance that temperatures will remain above average across California and the rest of the U.S. West, according to temperature outlooks from the NWS Climate Prediction Center. Outlooks anticipate above-average temperatures in this region through at least March 24. Meanwhile, arctic air is descending into the Midwest early next week, plunging temperatures by as much as 40 degrees from this week’s levels.