Southern California braces for 'very dangerous and unusual heat' plus oppressive humidity

Karen Garcia, Los Angeles Times on Sep 9, 2026

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LOS ANGELES — Punishingly hot temperatures coupled with drastically high humidity will peak Wednesday, making temperatures feel even more intense than previously blistering days, with real relief not expected to arrive until Friday.

Public health officials warn that the unusually high temperatures and humidity raise the risk of heat-related illnesses, particularly among older people and those with medical conditions.

"The temperatures we're going to see today are going to be extreme heat warning temperatures regardless of the humidity," said Bryan Lewis, meteorologist with the National Weather Service's Oxnard office. "But that humidity certainly adds to the discomfort and the 'real feel' heat," he added.

The sizzling temperatures are brought on by a combination of a strong upper-level ridge of high pressure coming from Arizona and an offshore flow coming from the north and east.

This one-two punch will bring temperatures about 8 degrees higher than normal to areas south of Point Conception and a whopping 10 to 15 degrees higher to the north.

As a result, the forecast calls for maximum temperatures of mid- to upper 80s at the beaches, 90s across the rest of the coast and 100 to 108 degrees for the valleys.

Forecasters say there will be little relief for Southern Californians when the sun goes down as temperatures will remain uncomfortably warm at night.

Experts say the heat will feel even worse due to higher-than-normal humidity brought by the remnants of former-Tropical Storm Marie and warm temperatures coming from the ocean.

Lewis said dew point temperatures are projected to be in the 70s for most of Los Angeles and Ventura counties.

The higher the dew point rises, the greater the amount of moisture in the air, according to the National Weather Service. Generally, a dew point of 55 or less feels comfortable, while 65 or higher can feel oppressive.

The National Weather Service office in Oxnard, which issues forecasts for Los Angeles County, doesn't keep historic records for dew point or relative humidity, he added.

"But from my recollection, we generally sit somewhere between the mid-50s to maybe the low 60s," Lewis said. "Even if it's a 10- to 15-degree difference in dew point, it's pretty drastic."

Extreme heat warnings are in effect until Thursday for a majority of Los Angeles County — from the Malibu coast, to the San Fernando Valley and all the way south to the Palos Verdes Hills.

The humidity makes this heat much more dangerous than previous heat waves, according to Los Angeles County Public health officials.

Public health officials say all residents should limit their outdoor activities during the afternoon, seek air-conditioned spaces, and take lots of breaks. Residents are advised to check on those at high risk for heat-related illness, including people with preexisting conditions, older adults, pregnant women, children and anyone without access to air conditioning.

Unsafe weather conditions can create an added heat stress by forcing a person's body to adjust to maintain a stable core temperature, said Dr. David Eisenman, a professor at the David Geffen School of Medicine and UCLA Fielding School of Public Health.

A person's body is working to maintain 98.6 degrees and if it gets hotter and more humid outside, the body has to work harder to maintain that stable temperature, he said.

To aid the body in getting as close to stable temperature as possible, Eisenman said people can practice "skin wetting" by keeping as much bare skin continuously damp as possible.

Use a spray bottle, for example, to mist water directly onto a person's face, neck and forearms, he said. Repeat every five to 10 minutes to keep skin visibly wet.

People can also soak their clothing in cold water or apply an iced or chilled damp towel to their body.

Forecasters say temperatures should drop by five degrees on Thursday but the high humidity will continue to loom through the day.

By Friday, Lewis said, the region will experience another cooling trend — with temperatures dropping another 5 degrees — but the bigger relief will be the decreasing humidity that will probably "be a lot closer to what we normally expect in terms of that amount of moisture in the air."

"Friday is when we'll start feeling it, and we'll also start to kind of lose some of that really humid tropical air," he said.