Southern California has seen some toasty Octobers, but this year’s start to the fall season has been marked by a persistent heat wave that’s shattered records and ushered in an unusual streak of 100 degree days.
The extreme heat is driven by a persistent high pressure ridge that has parked over the region causing sinking warming air with very little overnight relief. That is paired with down-sloping winds and uncharacteristically warm ocean temperatures driven in part by El Niño that has reduced Southern California’s sea breeze, frequently known as its natural air conditioning.
The unusually high temperatures won’t event relent much for those living along the coast.
“We’re going on day four of this really significant heat wave and we still have several more days of heat,” said Rose Schoenfeld, a meteorologist with the National Weather Service in Oxnard. “We do have heat events in October, but this streak of 100 plus days is definitely starting to become pretty notable.”
The average number of 100 degree days in downtown Los Angeles in a typical October has been closer to zero than one since the weather service began keeping records. So far this month, downtown is on a three-day streak of temperatures 100 degrees or higher and could hit a fourth, according to the weather service.
If the mercury hits 100 degrees on Monday, “that’ll be the longest streak of 100 or higher days in October that we’ve seen for the period of record for that site,” Schoenfeld said. The weather service keeps records for downtown Los Angeles dating back to the 1800s.
The current heat wave has already broken daily heat records across the Southland.
The Burbank Airport hit 101 degrees on Sunday, breaking the previous record of 100 degrees set in 1964. Camarillo hit 99 degrees, inching past the previous record of 98 degrees set in 1953. And Oxnard hit 99 degrees on Sunday, shattering the daily record of 94 degrees set in 2023.
In Orange County, Anaheim hit 101 degrees on Sunday, blowing past the 98 degree record set in 2020.
San Diego hit 100 degrees, toppling a record of 97 degrees set in 1987. The Oceanside Harbor registered 98 degrees on Sunday, toppling the record of 97 degrees set in 1953. And Ramona hit 101, just past the record of 100 degrees set in 1987.
Temperatures between 15 and 22 degrees above normal are expected to persist through Thursday. Highs along the coasts and valleys will be in the 90s up to the low 100s in the coming days. Even the beaches will provide little relief with temperatures in the upper 80s.
The ocean is expected to bring its own dangers beginning Tuesday with elevated morning and evening tides and elevated surf as a result of Hurricane Rachel, located several hundred miles off the coast of Baja California.
The weather service is warning of dangerous rip currents and elevated surf of 3 to 6 feet on Catalina and Santa Barbara Islands and Los Angeles and Ventura County beaches. The most susceptible areas will be Long Beach and the Avalon Harbor on Tuesday and Wednesday and then Malibu through Ventura County Wednesday through Friday.
“Moderate flooding of sea water is a possibility over some vulnerable low-lying coastal areas, especially around the morning and evening high tides, including over beach parking lots, bike paths, and harbor walkways. Moderate beach erosion is possible to likely,” according to the weather service.
And those looking for relief won’t find it overnight.
It’ll still be warm after dark too, forecasters say, with the mercury only dipping into the upper 60s to mid-70s across much of the region. The weather service in Oxnard and San Diego issued extreme heat warnings through 8 p.m. Thursday, cautioning of the risk of heat related illnesses.
“We’re going on day four of this really significant heat wave and we still have several more days of heat,” Schoenfeld said, pointing to a lack of overnight recovery and days of hot weather that can “really build and stress the body over time, especially for the elderly and other vulnerable folks like the very young.”
The heat is expected to relent by the weekend with temperatures in the mid-80s and even a chance of light showers on Sunday as Hurricane Rachel continues its path across the Pacific Ocean.
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