The National Weather Service escalated its heat alert for all of Los Angeles County on Sunday, Aug. 23, issuing an extreme heat watch that takes effect Wednesday, Aug. 26, at 10 a.m. and runs through at least Friday evening.

Temperatures in the hottest inland areas could reach 112 degrees during the watch period, according to KTLA. A strengthening ridge of high pressure is driving the event, and forecasts have trended hotter in recent days, with several degrees added to projected highs.

The heat wave is expected to peak between Tuesday, Aug. 25, and Thursday, Aug. 27. On Sunday, downtown Los Angeles was forecast to reach 94 to 96 degrees, with the San Fernando Valley hitting 106 and the Antelope and Santa Clarita valleys also topping 100, Spectrum News reported.

A heat advisory is already in effect and continues through 10 a.m. Tuesday, Aug. 25, when the watch takes over.

The watch covers every zone in the county, from the beaches and Palos Verdes Peninsula to Malibu and the Catalina and Santa Barbara islands. Overnight lows in the valleys are expected to stay in the 70s, offering little relief after sundown.

Wildfire danger rises alongside the heat

The NWS warned of elevated wildfire risk during the heat wave, noting an increased chance of large, plume-dominated fire behavior across the region. No major wind events are expected, with afternoon and evening gusts in the Antelope Valley staying in the usual 15-to-25-mph range.

Air quality is also deteriorating. Unhealthy conditions were reported Sunday morning around Azusa, Rancho Cucamonga and Redlands, though areas closer to the coast fared better.

What residents should do

In an Aug. 7 advisory issued during a prior heat wave, LA County Health Officer Muntu Davis said that "heat causes more deaths in the U.S. annually than floods, storms, and lightning combined," urging older adults, young children, outdoor workers and people with chronic conditions to take extra precautions. The same guidance applies now.

Health officials advise residents to drink plenty of fluids, stay in air-conditioned spaces during the hottest hours and check on neighbors and relatives. Children and pets should never be left in parked vehicles.

Residents without air conditioning can find free cooling centers, splash pads and community pools by visiting ready.lacounty.gov/heat or calling 211. Anyone experiencing symptoms of heat stroke, including a body temperature of 103 degrees or higher, confusion, dizziness or rapid heartbeat, should call 911 immediately.

Temperatures are expected to remain extremely hot through at least next weekend, even after the watch expires.