California Heat Advisory in Effect Through Monday as Temperatures Reach Triple Digits

At 2:58 a.m. on Wednesday, July 21, 2026, the National Weather Service (NWS) Los Angeles/Oxnard office released a heat advisory that will remain in effect until Monday at 8 p.m. The advisory covers a wide area of Southern and Central California, including the Cuyama Valley, Santa Clarita Valley, Santa Lucia Mountains, Southern Salinas Valley, interior valleys and mountains of San Luis Obispo County, Santa Ynez Valley and Mountains, Santa Barbara County interior mountains, Lake Casitas, Ojai Valley, central Ventura County valleys, western and eastern Santa Monica Mountains recreational areas, Calabasas, Agoura Hills, western and eastern San Fernando Valley, southeastern Ventura County valleys, Santa Susana Mountains, northern, southern and central Ventura County mountains, the Interstate 5 corridor, western and eastern San Gabriel Mountains, Highway 14 corridor, western Antelope Valley foothills, eastern Antelope Valley foothills, and Los Angeles.

The NWS notes that daytime temperatures will range between 97°F and 107°F, with overnight temperatures remaining warm and providing little relief. The advisory highlights a high risk for heat illness, especially for sensitive groups such as the very young, the very old, people without air conditioning, and those who are active outdoors.

To reduce the risk of heat‑related illness, the NWS recommends staying hydrated, seeking cool shelter, avoiding prolonged sun exposure, checking on relatives and neighbors, and ensuring that children and pets are not left unattended in vehicles. The advisory also advises people who work or spend time outdoors to take extra precautions, reschedule strenuous activities to early morning or evening, and wear lightweight, loose‑fitting clothing. In an emergency, the NWS urges people to call 911.

The Occupational Safety and Health Administration (OSHA) recommends scheduling frequent rest breaks in shaded or air‑conditioned environments for outdoor workers. OSHA also advises that anyone who becomes overwhelmed by heat should be moved to a cool, shaded location.

California has experienced a growing number of heat waves in recent years. NASA Science reports that heat waves in Southern California have increased in frequency, duration, and intensity over recent decades. The World Meteorological Organization notes that heat waves are becoming more frequent worldwide, with record‑breaking temperatures reported in North America, Europe, and Asia. The National Oceanic and Atmospheric Administration (NOAA) has issued similar heat advisories in the past, and the NWS is tasked with providing warnings to protect public safety.

Heat waves can have broad impacts on California’s economy and infrastructure. According to Wikipedia, extreme heat can reduce labor productivity, disrupt agricultural and industrial processes, damage infrastructure, and increase the risk of wildfires. The heat advisory is part of the NWS’s effort to mitigate these risks by informing residents and businesses of the impending conditions.

The 2021 Western North America heat wave, which set record temperatures in California and neighboring states, highlighted the vulnerability of the region to extreme heat. According to Wikipedia, the heat wave caused widespread damage and increased wildfire risk.

The current advisory follows a pattern of heat warnings issued by the NWS in recent weeks, as the state continues to experience record‑breaking temperatures. The NWS office has issued similar advisories for other parts of California during the summer.

The advisory remains in effect until Monday at 8 p.m. Residents and businesses in the covered areas are encouraged to monitor updates from the NWS, local health departments, and emergency management agencies. By following the recommended precautions, Californians can reduce the risk of heat‑related illness during this period of elevated temperatures. Residents are encouraged to stay informed through local media and the NWS website for any updates.