Forget hot drinks and fall sweaters, this fall in Southern California will feel like a continuation of summer.
The extreme heat is driven by a persistent ridge of high pressure residing in the region, causing warm air to sink with little relief overnight. Meanwhile, downslope winds and unusually warm ocean temperatures — driven in part by El Niño, which reduces ocean breezes in Southern California and is often called natural air conditioning.
Climate experts say the South has experienced hot Octobers in the past, but if it feels different, that’s because it is.
Hot weather is expected to last for much of the week, keeping people indoors and forcing those without air conditioning to seek refuge in cooling centers.
“This is not going to be a heat wave that suddenly breaks out in dramatic fashion,” said Daniel Swain, a climate scientist with the University of California Department of Agriculture and Natural Resources. “Temperatures are likely to be significantly above average for some time to come. This could end up being one of the warmest Octobers on record, at least in some areas of Southern California, and perhaps much of California and the West as well.”
Here’s what we know:
How hot will it be?
Temperatures are expected to remain 15 to 22 degrees above normal on Thursday. Over the next few days, highs along the coast and in the valleys will reach the 90s and lows in the 100s. With temperatures in the high 80s, not even the beach can relieve the stress.
Those seeking relief won’t find answers overnight.
Forecasters say the weather will remain warm after dark, with temperatures only dipping into the 60s and 70s in much of the region. Weather services in Oxnard and San Diego have issued extreme heat warnings until 8 p.m. Thursday, warning people of the risk of heat-related illness.
Rose Schoenfeld, a meteorologist with the National Weather Service in Oxnard, said the lack of overnight recovery and days of hot weather “can really put a strain on the body over time, especially on older adults and other vulnerable populations like young children.”
The Los Angeles Department of Public Health urges residents to stay hydrated, avoid going outside during the hottest times of the day, use an umbrella and wear light clothing if they must go out, and rest frequently in air-conditioned areas. There are dozens of cooling centers open across the county.
Heat breaks record
The heat wave broke several records, including in downtown Los Angeles, where temperatures reached 100 degrees or higher four consecutive times, the longest such streak in October on record.
Downtown Los Angeles broke its single-day high temperature record on Monday with a temperature of 104 degrees, surpassing the previous record of 101 degrees set in 1954 and set in 1971.
Schoenfeld said the current number of October days with temperatures above 100 degrees downtown is on par with 1958 and 1971, but if temperatures reach 100 degrees on Tuesday, downtown could exceed those years.
According to the weather service, the average number of 100-degree days in October in downtown Los Angeles has been closer to 0 than 1 since the weather service began keeping records in the late 1800s.
Other high temperature records also fell over the weekend.
Burbank Airport reached 101 flights on Sunday, breaking the previous record of 100 flights set in 1964. Camarillo Airport reached 99 flights, slightly surpassing the previous record of 98 flights set in 1953. Oxnard reached 99 on Sunday, breaking the previous daily record of 94 set in 2023.
In Orange County, Anaheim hit 101 degrees on Sunday, breaking the previous record of 98 degrees set in 2020.
The temperature in San Diego reached 100 degrees, breaking the previous record of 97 degrees set in 1987. The temperature at Oceanside Harbor reached 98 degrees on Sunday, breaking the previous record of 97 degrees set in 1953. Ramona reached 101 degrees, just surpassing the previous record of 100 degrees set in 1987.
Is October usually this hot?
Swain said October can be hot, but it generally doesn’t last that long.
Temperatures along the California coast in September and October are typically warmer than in June or even July because the marine layer stays cooler during these months. He said the ocean layer usually recedes at this time of year, causing temperatures to rise, especially along the coast.
“But even by that standard, it’s extraordinary,” he said. “Not just because there are individual days where it’s very hot during the day and at night, but because we’ve had these extreme temperatures for multiple days in a row and that’s continuing and only slowly receding.”
“So, is this completely unprecedented? No. Is this typical for October? Absolutely not,” he added.
When will the scorching temperatures end?
The hot weather is expected to ease by the weekend, with temperatures reaching the mid-80s, and there may even be a chance of light showers on Sunday as Hurricane Rachel continues to move across the Pacific.
But Swain said models show temperatures won’t drop as much as October continues.
“It’s not a cool fall by any means,” he said.