California prepares for extreme heat of up to 42 °C, warning the population: “Stay out of the sun”

A heat warning is expected to be issued for parts of California this week, with meteorologists predicting sweltering temperatures of up to 42 degrees Celsius between Monday and Thursday.

The National Weather Service urged residents of Northern, Central and Southern California to “drink plenty of fluids, stay in an air-conditioned room, [and] Avoid the sun” as “dangerous heat” and thus a high risk of heat-related illnesses are to be expected in the regions in the coming days.

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Temperatures could reach 105 degrees in parts of Central California, including Fresno, San Joaquin and Porterville, the NWS said. A heat advisory is expected to be in effect for the region from 11 a.m. PT Wednesday to 8 p.m. PT Thursday.

People walk at sunset in Los Angeles on July 24, 2023. Temperatures of up to 42 degrees Celsius are expected in some regions of California.

FREDERIC J. BROWN/AFP via Getty Images

A heat advisory is in effect for the slopes of the Mojave Desert during this period, and a wind advisory is in effect until 7 a.m. PT Monday. Temperatures of up to 97 degrees and gusty winds that can blow over unsecured objects are expected in the region.

“Tree branches could be downed and some power outages could occur. Heat-related illnesses increase significantly during extreme heat,” the government agency wrote.

Winds could make driving difficult on Highway 14, Highway 58 below Tehachapi Pass and Highway 178 below Walker Pass.

Temperatures of up to 100 degrees Fahrenheit are expected in Indian Wells and the Mojave Desert – including the California City, Ridgecrest, Edwards Air Force Base, Rosamond, Inyokern and Randsburg areas – and a heat advisory is in effect from 11 a.m. PT Wednesday to 8 p.m. PT Thursday.

The same weather warning has also been issued for the mountains on the west side north and south of Highway 198, where temperatures are expected to reach 40 degrees Celsius. In the Kern River Valley, where the same weather warning is in effect, temperatures of up to 41 degrees Celsius can be expected.

The NWS said temperatures between 95 and 108 degrees Fahrenheit are expected in the following areas, with the highest temperatures expected Wednesday: Carquinez Strait and Delta, Sacramento Valley, Mother Lode, mountains from southwest Shasta County to western Colusa County, northeastern foothills, northern San Joaquin Valley and parts of Shasta County.

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The NWS warned that overnight would bring little relief from the heat, with lows ranging between 15 and 24 degrees. “Waterways in the region will continue to be cold and fast-flowing, creating dangerous conditions for those seeking refreshment in rivers and lakes,” the agency wrote, adding, “Hot temperatures could persist into Friday.”

Heat can cause serious health problems, some of which can be fatal – including heat exhaustion and heat stroke. Heat exhaustion is more likely to affect the elderly, people with high blood pressure, and people who work outdoors in high temperatures. Common symptoms of heat exhaustion include headache, nausea, dizziness, weakness, thirst, heavy sweating, and high body temperature.

Heat stroke is more serious. When the body can no longer control its temperature – which is ideally around 37 degrees – the sweating mechanism designed to cool it down fails and the body temperature can rise above 38 degrees within 10 to 15 minutes.

At this point, the body's internal organs begin to swell and fail, which can lead to permanent disability or even death. Symptoms of heat stroke include confusion, loss of consciousness, profuse sweating, seizures, and high body temperature.