Heat advisories and an extreme heat warning will take effect Wednesday as a prolonged heat wave is expected to bring triple-digit temperatures to inland areas of Southern California.
“Hotter than normal conditions will dominate the foreseeable future,” the National Weather Service said. “The hot daytime and warm night conditions will bring elevated risks for heat illness.”
The weather service on Tuesday replaced an earlier extreme heat watch with a heat advisory for the Los Angeles County valleys and mountains, effective from 10 a.m. Wednesday through 8 p.m. Monday. Forecasters expect highs of 97 to 107 degrees with unusually warm overnight temperatures.
The advisory covers the Santa Clarita Valley, the San Fernando Valley, the San Gabriel Valley, the Santa Susana Mountains, the Interstate 5 corridor, the western and eastern San Gabriel Mountains, the western and eastern Antelope Valley foothills and other mountain communities.
The Antelope Valley, meanwhile, was upgraded from an extreme heat watch to an extreme heat warning effective from 10 a.m. Thursday through 8 p.m. Monday. Highs there are expected to range from 100 to 108 degrees.
The heat advisory for the Los Angeles County inland coast, including downtown Los Angeles, will remain in effect from 10 a.m. Wednesday through 8 p.m. Monday, with highs of 88 to 96 degrees.
Forecasters said temperatures will increase only slightly Tuesday before climbing more sharply Wednesday. By then, highs are expected to reach the 80s in coastal areas away from the beaches and the 90s to low 100s in the valleys before peaking Thursday.
“The heat kicks into gear on Wednesday as the weakening onshore trends begin,” the NWS said.
Highs in the lower mountain elevations and far inland areas are forecast to reach around 100 to 103 degrees, with most locations running about 4 to 8 degrees above seasonal averages.
Thursday is expected to be the hottest day. Overnight temperatures also are expected to remain well above normal in many valleys.
Forecasters said the prolonged heat wave is expected to continue into early next week with little day-to-day change in temperatures.
Daytime highs and overnight lows will remain well above normal, and humid conditions will add to the discomfort. Some cooling is possible Friday, but forecasters said it may be limited.
The city of Los Angeles urged residents to take precautions during the heat event by staying hydrated, seeking shade or air-conditioned buildings and limiting strenuous outdoor activities to the morning or evening hours whenever possible.
Officials also encouraged residents to check on older adults, neighbors and others who may be vulnerable to extreme heat, and reminded the public never to leave children or pets unattended in vehicles.
People without access to air conditioning were encouraged to seek relief at public libraries, recreation facilities, senior centers or other public buildings.
Information about cooling centers is available by calling 311 or online through the city’s emergency management website at emergency.lacity.gov/heat.