Southern California will enter a dangerous and prolonged heat wave Friday, with temperatures reaching triple digits in some areas and extreme heat expected to persist through next week.
The National Weather Service issued an Extreme Heat Warning from 10 a.m. Friday through 8 p.m. Thursday for coastal and valley areas of Los Angeles County.
Temperatures could reach 90 degrees along the coast and 105 degrees in the valleys during the warning period, according to the NWS.
Friday is expected to bring temperatures 10 to 15 degrees above normal, with highs in the mid- to upper 80s across most coastal areas and the lower to mid-90s along parts of the Los Angeles County coast. Valley temperatures are expected to range from the upper 90s to 105 degrees.
“The well advertised long duration heat wave kicks off on Friday,” according to the NWS.
Saturday is expected to be the hottest day of the next seven, with temperatures rising another 2 to 4 degrees in coastal and valley areas and locally as much as 6 degrees, forecasters said.
Most coastal areas are expected to reach the 90s Saturday, while valley temperatures could range from 100 to 107 degrees, or about 15 to 20 degrees above normal.
“This will make Saturday the hottest of the next 7,” according to the NWS.
The heat is expected to ease only slightly Sunday, with temperatures remaining generally 10 to 15 degrees above normal Monday through Wednesday. Above-normal overnight temperatures could also limit relief from the daytime heat, forecasters said.
Extreme Heat Warnings will also be in effect from 10 a.m. Friday through 8 p.m. Thursday for coastal and inland Orange County.
High temperatures in coastal Orange County are expected to range from the mid-80s to around 90 near the coast and reach the lower to mid-90s near higher coastal terrain, according to the NWS. Inland Orange County highs are expected to range from the mid-90s to near 100.
Overnight lows in both coastal and inland Orange County are expected to remain mostly in the lower to mid-70s.
“Even through this heat wave will not likely produce record heat it will still be very dangerous due to the prolonged duration of the event,” according to the NWS. “The relentless heat will have a hazardous wearing down effect on people, (especially) the very young and old.”
Humidity is expected to increase Monday through Wednesday as moisture from Hurricane Rachel moves into the region, with a 5% to 15% chance of afternoon showers or thunderstorms in the mountains, according to the weather service.
Forecasters said the latest long-range models indicate conditions could begin improving around Oct. 10.
The Los Angeles County Department of Public Health urged residents to stay hydrated, avoid outdoor activity during the hottest hours when possible and use air-conditioned spaces or cooling centers if they are unable to keep their homes cool.
“Heat causes more deaths in the U.S. annually than floods, storms, and lightning combined. Those most likely to get ill during the heat include older adults, young children, outdoor workers, athletes, and individuals with chronic medical conditions,” Los Angeles County Health Officer Dr. Muntu Davis said.
“Remember, your safety and the safety of others is crucial during extreme heat conditions. If you or someone around you experiences symptoms of heat stroke or heat exhaustion, such as dizziness, nausea, rapid heartbeat, confusion, or passing out, seek medical help immediately.”
County health officials also urged residents to check on people at higher risk of heat-related illness, including older adults, children, pregnant people, people with chronic health conditions, those who live alone and outdoor workers.
Residents without access to air conditioning can find cooling centers, splash pads and community pools by calling 211, county officials said.
The city of Los Angeles Emergency Management Department said temperatures could reach 100 degrees in downtown Los Angeles, 90 degrees at the coast and 105 degrees in the valleys during the heat wave.
City officials urged residents without air conditioning to use public libraries, recreation facilities, senior centers or other air-conditioned public buildings. Residents can call 311 to locate nearby cooling facilities or use the city’s Cool Spots LA online tool.
Officials also urged people working, exercising or spending extended periods outdoors to reschedule strenuous activities for the early morning or evening when possible, wear lightweight and loose-fitting clothing and take frequent breaks in shaded or air-conditioned areas.
Anyone experiencing possible heat stroke should be moved to a cool, shaded location and 911 should be called, city officials said.