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September starts with potential record heat for the Southwest and West Coast

Vaseline September 3, 2024

Summer will continue for a long time in September, with heat warnings expected to affect 26 million people on Wednesday, mainly in the southwest.

Temperatures in cities including Los Angeles, Las Vegas and Phoenix could be 10 to 20 degrees above normal starting on Tuesday and peaking on Thursday, according to federal weather forecasters and NBC News meteorologists.

A mass of warm air pressing down on Earth’s surface, called an upper ridge, is strengthening over the Southwest, blocking cool air from the Pacific Ocean. The result is dangerously hot conditions from California’s Central Valley east of San Francisco to the U.S.-Mexico border near Arizona.

“Temperatures are forecast to be above average across much of the West Coast, with the potential for several daily records,” the National Weather Service said in a special statement about the heat wave on Sunday.

The Los Angeles Weather Service reported Monday that temperatures of 100 to 113 degrees Fahrenheit are possible starting Wednesday, with the warmest areas likely to be in the western San Fernando Valley.

Los Angeles Mayor Karen Bass said Monday she is deploying the city’s resources, including “enhanced cooling centers” and emergency personnel, to prepare. The additional cooling centers will open Tuesday morning, her office said in a statement.

Public libraries, park facilities, recreation centers, senior centers, community pools and splash pads, and hydration stations and shade structures will be made available, her office said. A special cooling center, ReFresh Spot, with access to drinking water and showers, will be open 24 hours a day in Skid Row, it said.

An extreme heat warning was expected Wednesday through Friday for most of Southern California’s most populous counties: San Diego, Orange, Los Angeles, Ventura and Santa Barbara, and for the Inland Empire of desert and mountain communities that stretches nearly to Las Vegas.

The warnings will begin at the U.S.-Mexico border and extend up the coast to the jagged coastline near San Simeon, California, federal meteorologists said. They will extend east into Arizona and cover southern Nevada. The National Weather Service office for Las Vegas, where this summer was declared the warmest in recorded history, and a lower level extreme heat warning was issued for the same time, calling for temperatures as high as 108 degrees by midweek.

“Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun and keep in touch with family members and neighbors,” the weather service said in an urgent weather report about the heat wave.

The office responsible for Phoenix has also issued a heat warning for the last three days of the week. Monday’s emergency weather warning said “dangerously hot conditions are possible.”

An extreme heat warning describes impending heat that is a certainty and poses a “significant” threat to life, according to the National Weather Service. A warning is issued when such heat is likely but there is a day or two to prepare, the weather service says.

Meanwhile, normal to below-normal temperatures are expected along the East Coast, while thunderstorms are possible along the Texas Gulf Coast.

Heat in the West was unlikely to help dry, windy conditions in the northern Plains states, including Iowa, Nebraska, North Dakota, South Dakota, Kansas and Oklahoma. The region was covered by a federal “critical fire weather” forecast for the workweek.