Southern California is famous for sunshine, ocean breezes and a climate that often feels effortless. This week, however, much of the region has been experiencing something distinctly different.
An unusual combination of intense September heat and tropical moisture has pushed humidity to exceptionally high levels across Los Angeles and surrounding communities, leaving residents facing conditions that feel far more typical of Florida than Southern California.
Temperatures across large portions of the region climbed above 100 degrees Wednesday, while elevated humidity made the heat feel several degrees hotter. Coastal communities that normally provide an escape from inland heat have also been unusually warm and uncomfortable.
The result has been a Southern California weather pattern that is challenging one of the region’s most familiar expectations: that even the hottest days are usually accompanied by relatively dry air.
This time, the moisture is impossible to ignore.
Dew points reached unusually high levels in coastal areas including Long Beach, Huntington Beach and Newport Beach earlier this week. Meteorologists described the atmospheric moisture as among the most oppressive conditions they could remember experiencing in the region.
When Heat and Humidity Collide
High temperatures alone can put enormous stress on the body, but humidity creates an additional problem.
Sweating is one of the body’s most important cooling mechanisms. When the surrounding air contains large amounts of moisture, sweat does not evaporate as efficiently. That makes it more difficult for the body to release heat and maintain a safe internal temperature.
Los Angeles County health officials have warned residents to take the conditions seriously, particularly older adults, young children, pregnant women, outdoor workers and people with existing medical conditions. Officials have encouraged residents to limit strenuous outdoor activity during the hottest parts of the day, remain hydrated and spend time in air conditioned spaces whenever possible.
The weather has also provided little relief after sunset.
Warm overnight temperatures can become especially difficult because homes, buildings and city streets do not have as much time to cool before the next day begins. For residents without air conditioning, several consecutive warm nights can make a heat wave increasingly exhausting.
Tropical Moisture Reaches Southern California
Part of the unusual humidity has been connected to lingering tropical moisture associated with former Tropical Storm Marie.
The same weather system contributed to dangerous surf along the Southern California coastline, with large waves, strong currents and coastal flooding affecting communities from Los Angeles County through Orange County.
Waves reached as high as approximately 10 feet in some areas, while officials warned beachgoers about powerful rip currents. Newport Beach lifeguards carried out 177 rescues during one particularly active Saturday as rough ocean conditions reached the coast.
The ocean’s impact became especially visible in Malibu.
A large sinkhole opened near a coastal home on Tuesday after erosion and flooding damaged the property area. Emergency crews also responded to a gas leak associated with the collapse, while access to several nearby homes was temporarily restricted because of safety concerns.
Together, the coastal damage and tropical humidity have created one of the more unusual weather stretches Southern California has experienced this summer.
A Different Kind of Los Angeles Summer
For generations, Southern California’s climate has been part of its identity.
Los Angeles summers can certainly become extremely hot, particularly across the San Fernando Valley, Inland Empire and other interior communities. The difference has traditionally been the relatively dry atmosphere.
That is why this week’s humidity has felt so noticeable.
Southern California homes, neighborhoods and daily routines were largely built around a climate where extreme moisture was uncommon. Many older homes and apartments near the coast were constructed without central air conditioning because ocean breezes historically provided natural cooling.
When those breezes weaken and tropical moisture moves into the region, residents can quickly feel the difference.
Meteorologists have attributed the current conditions to several atmospheric factors, including high pressure, offshore flow and tropical moisture. The combination has limited some of the cooling influence residents normally receive from the Pacific Ocean.
Relief Is Expected, But Not Immediately
Forecasters expect temperatures to begin gradually declining, with more noticeable relief arriving as humidity decreases.
Southern California could see temperatures fall several degrees Thursday, although humid conditions may remain. By Friday, forecasts suggest that both temperatures and atmospheric moisture should move closer to what residents typically expect for the region.
Until then, health officials are urging people not to underestimate the weather simply because they are accustomed to Southern California heat.
Drinking water throughout the day, reducing afternoon outdoor activity, wearing lightweight clothing and checking on vulnerable relatives and neighbors can make an important difference.
Residents without air conditioning are encouraged to use libraries, shopping centers, cooling centers and other climate controlled public spaces during the hottest hours.
Southern California’s Weather Is Becoming Harder to Predict
Perhaps the most striking part of this week’s weather is how unfamiliar it feels.
Southern California remains one of the world’s most recognizable climates, but recent extremes have shown how quickly conditions can change. Within the same stretch of coastline, residents have experienced triple digit temperatures, tropical humidity, flooding, powerful surf and dangerous rip currents.
For many Angelenos, this week will be remembered less for a single temperature reading and more for the feeling of stepping outside and realizing that familiar Southern California air suddenly felt completely different.
The sunshine is still here.
The dry heat, at least for the moment, is not.
