David Contreras places a cold towel on his neck to cool off while talking to ARCHES outreach workers as temperatures exceed 100 degrees in Salem, Oregon on Thursday, Aug. 12, 2021. Salem Heatwave 123
San Diego, California – California is heading into a blistering heatwave this week, with forecasters warning of potentially record-breaking temperatures across large swaths of the state, particularly in inland and desert areas. The heat is expected to intensify as the week progresses, culminating in dangerous triple-digit highs by Friday, according to the National Weather Service (NWS).
While much of Southern California has already seen warm conditions in recent days, a sharp rise in temperatures is forecast to hit valleys and desert regions especially hard. By Friday, highs are expected to reach or exceed 100 degrees in areas such as Palmdale, Lancaster, Paso Robles, and Ojai. The NWS says there is a 30% to 40% chance that calendar day heat records could be broken in some of these locations.
In Northern California, residents in the Sacramento Valley should also prepare for sweltering conditions. After enjoying milder weather earlier in the week, temperatures are forecast to spike dramatically—from the low 80s on Monday to a staggering 104 degrees by Friday. The NWS has issued an Extreme Heat Watch for the area, effective Friday morning through Saturday evening, citing widespread major heat risk with little overnight relief expected.
Temperatures in the valley could range from 99 to 109 degrees during the peak of the heatwave, with nighttime lows only dropping into the mid-60s to mid-70s. These conditions pose a significant risk for heat-related illnesses, especially for those working or engaging in outdoor activities.
Despite the oppressive heat inland, California’s coast will remain more temperate, at least through the early part of the week. San Diego, in particular, is forecast to avoid the worst of the heatwave, with coastal breezes and relatively mild temperatures keeping conditions pleasant. The city continues to offer a welcome respite for those seeking relief, with no extreme weather alerts currently in effect.
Authorities are urging residents across the state to take precautions: stay hydrated, avoid prolonged exposure to the sun, and seek air-conditioned environments whenever possible. They also warn against entering rivers and lakes in search of relief, as many bodies of water remain cold and fast-moving—posing significant risks even amid soaring air temperatures.
As California heads into what could be the hottest stretch of 2025 so far, officials are emphasizing preparation and caution to avoid preventable heat-related emergencies.
