An Extreme Heat Warning is currently in effect for a broad swath of Southern California, issued jointly by the National Weather Service Los Angeles/Oxnard CA, NWS Hanford CA, and NWS San Diego CA. The warning became active on Monday, July 28, 2026, at 9:57 a.m. PDT and remains in effect through Sunday, August 2, 2026, at 8:00 p.m. PDT. Anyone in the affected zones should treat this warning as ongoing until that expiration time passes.
The areas covered under this warning include the Interstate 5 Corridor, Western Antelope Valley Foothills, Cuyama Valley, Indian Wells Valley, San Diego County Mountains, San Diego County Inland Valleys, Santa Ana Mountains and Foothills, Apple and Lucerne Valleys, Coachella Valley, Orange County Inland, Riverside County Mountains, and San Bernardino and Riverside County Valleys, including the Inland Empire. This is a wide geographic footprint spanning desert, mountain, valley, and suburban communities across Southern California.
What the National Weather Service Is Telling Residents Right Now
The National Weather Service is providing direct, actionable guidance for the duration of this warning. The core recommendations are straightforward: drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. Those simple steps cover the majority of heat-related risk for most residents.
One of the most urgent reminders in the official alert concerns vehicles. Do not leave young children or pets in unattended cars. Car interiors can reach lethal temperatures within minutes, even when outside conditions may not feel extreme. This is not a secondary concern, it is one of the most preventable causes of heat-related death during warning events.
For those who must be outdoors, NWS instructs residents to wear lightweight and loose-fitting clothing, and to limit strenuous physical activity to early morning or evening hours when temperatures are lower. Knowing the warning signs of heat exhaustion and heat stroke, and taking action when those symptoms appear, is essential throughout the warning period.
For outdoor workers, the alert specifically references guidance from the Occupational Safety and Health Administration (OSHA), which recommends scheduling frequent rest breaks in shaded or air-conditioned environments. If anyone is overcome by heat, move them to a cool, shaded location immediately. Heat stroke is a medical emergency: call 9-1-1.
If you do not have air conditioning at home or are without shelter, call 2-1-1 for assistance locating appropriate cooling shelter in your area. This resource is available throughout the warning period and is specifically cited in the NWS alert for residents who need it.
Preparedness Context for the Warning Period
Extended heat warnings like this one, lasting nearly a full week across populated valleys and mountain communities, are exactly the scenario that disaster preparedness planning is built around. At usriskradar.com, we consistently emphasize that household preparedness for extreme heat means more than having water on hand. It means knowing where your nearest cooling center is before you need it, having a plan for checking on elderly or isolated neighbors, and understanding when to call for emergency help rather than waiting. The NWS alert will be updated as conditions evolve, so monitor the latest forecasts from the National Weather Service throughout this warning period and follow any new guidance as it is issued.
For the fundamentals that apply beyond this specific alert, see our Power Outage Preparedness guide.
Source: National Weather Service (NWS Los Angeles/Oxnard CA, NWS Hanford CA, NWS San Diego CA). Active alert data retrieved 2026-07-28 22:00 UTC via api.weather.gov.
