Forget hot drinks and fall sweaters: this fall in Southern California has been marked by what feels like a continuation of summer.
The extreme heat is being driven by a persistent ridge of high pressure that has parked itself over the region, causing warm air to drop with very little relief overnight. Added to this are downslope winds and unusually warm ocean temperatures – caused in part by an El Niño phenomenon that reduced Southern California’s sea breeze, often known as natural air conditioning.
The Southland has experienced warm Octobers in the past, but if this feels different, that’s because it is, according to climate experts.
The hot weather, which has kept people indoors and forced those without air conditioning to seek shelter in cooling centers, is expected to last much of the week.
“It’s not going to be a heat wave that suddenly breaks out in a dramatic way,” said Daniel Swain, a climate scientist at UC Agriculture and Natural Resources. “It’s likely to remain significantly warmer than average for some time to come. This will likely end up being, at least in parts of Southern California, one of the warmest Octobers on record, and perhaps across more of California and the West as well.”
Here’s what we know:
What temperature will it be?
Temperatures between 15 and 22 degrees above normal are expected to persist through Thursday. Highs along coasts and valleys will be in the 90s and reach the 100s in the coming days. Even the beaches will provide little relief, with temperatures hovering in the 80s.
And those looking for relief won’t find it overnight.
It will still be warm after dark, forecasters say, with the mercury only dipping into the 60s to mid-70s across much of the region. Weather departments in Oxnard and San Diego issued extreme heat warnings until 8 p.m. Thursday, warning of the risk of heat-related illnesses.
A lack of nighttime recovery and hot weather days can “really strain and stress the body over time, especially for older adults and other vulnerable people like the very young,” said Rose Schoenfeld, a meteorologist with the National Weather Service in Oxnard.
The Los Angeles Department of Public Health urges residents to stay hydrated, avoid going outside during the hottest hours of the day, use an umbrella and wear light clothing if you must go out – and take frequent breaks in air-conditioned spaces. The county has dozens of cooling centers open.
The heat broke records
The heat wave shattered several records, including in downtown Los Angeles, which is experiencing a streak of four straight days of temperatures of 100 degrees or higher – the longest consecutive streak in October since records began.
Downtown Los Angeles broke a daily heat record on Monday, with the mercury reaching 104, breaking the previous record of 101 set in 1954 and matched in 1971.
Downtown is currently tied for the most days with temperatures above 100 degrees in October with those in 1958 and 1971, but could surpass those years if the mercury hits 100 degrees on Tuesday, according to Schoenfeld.
The average number of 100-degree temperature days in downtown Los Angeles during a typical October is closer to zero than one since the weather service began keeping records in the late 1800s, according to the weather service.
On Monday, UCLA reached 100 degrees, breaking the previous daily record of 99 set in 1953. Woodland Hills reached 106, slightly surpassing the previous record of 105 set in 2025. Camarillo and Oxnard reached 99 and 98, breaking records of 98 and 94 degrees, respectively.
In Orange County, Anaheim reached 104 degrees on Monday, surpassing the previous record of 99 set in 2020. Santa Ana reached 106, breaking a 73-year-old daily record of 103 degrees.
In San Diego County, Vista reached 103 degrees, breaking a record of 98 set in 1987. Chula Vista reached 99 degrees, surpassing the record of 90 degrees set in 2020. Escondido also broke a record of 101 set in 2020 on Monday when the mercury rose to 106. Ramona set a new daily record of 101, breaking the previous record of 98 set in 2024.
Is it usually this hot in October?
It can be hot in October, but it’s usually not this sweltering for this long, according to Swain.
California often experiences higher temperatures in September and October along the coast than in June and even July due to the marine layer that keeps things cooler during these months. The marine layer typically recedes at this time of year, leading to higher temperatures, particularly along the coast, he explained.
“But even at that level, it’s been extraordinary,” he said. “Not just because it has been very hot day and night some days, but because there have been several days in a row where we have reached these extreme temperatures, and it continues and only slowly fades away.”
When will the scorching temperatures end?
The heat is expected to ease a bit by the weekend with temperatures hovering around the 80s and even a chance of light showers on Sunday as Hurricane Rachel continues its path through the Pacific Ocean.
But Swain said models suggest temperatures won’t drop as much as October continues.
“Is this completely unprecedented? No. Is this typical of October? Certainly not,” he added.
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