A long-running heat wave that has already shattered previous records across the U.S. will persist, baking parts of the West with dangerous temperatures that will soar into the 100s and holding the East in its hot and humid grip throughout the week, forecasters said Sunday.

An excessive heat warning — the National Weather Service's highest alert — was in effect for about 36 million people, or about 10% of the population, said NWS meteorologist Bryan Jackson. Dozens of locations in the West and Pacific Northwest were expected to tie or break previous heat records, he said.

That was certainly the case over the weekend: Many areas in Northern California surpassed 110 degrees (43.3 C), with the city of Redding topping out at a record 119 (48.3 C). Phoenix set a new daily record Sunday for the warmest low temperature: it never got below 92 F (33.3 C).

Las Vegas on Saturday tied the record of 115 F (46 C), last reached in 2007, and on Sunday the city was flirting with a record high of 118 F (47.7 C).

Temperatures in Oregon were expected to exceed 100 degrees Fahrenheit (37.7 degrees Celsius) on Sunday and soar as high as 115 degrees (46.1 C) in some parts of California, Jackson said. On the more-humid East Coast, temperatures above 100 degrees were expected, though no excessive heat advisories were in effect for the region on Sunday.

On Saturday, Raleigh, North Carolina, reached an all-time record high of 106 degrees F (41.1 C), with a maximum heat index of 118 F (47.7 C), he said.

"Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors," read a National Weather Service advisory for the Baltimore area. "Young children and pets should never be left unattended in vehicles under any circumstances."

Heat records shattered across the Southwest

Rare heat advisories were extended even into higher elevations including around Lake Tahoe, on the border of California and Nevada, with the National Weather Service in Reno, Nevada, warning of "major heat risk impacts, even in the mountains."

"How hot are we talking? Well, high temperatures across (western Nevada and northeastern California) won't get below 100 degrees (37.8 C) until next weekend," the service posted online. "And unfortunately, there won't be much relief overnight either."

Indeed, Reno hit a high of 104 F (40 C) on Saturday, smashing the old record of 101 F (38.3 C).

More extreme highs are in the near forecast, including 129 F (53.8 C) for Sunday at Furnace Creek, California, in Death Valley National Park, and then around 130 F (54.4 C) through Wednesday.

The hottest temperature ever officially recorded on Earth was 134 F (56.67 C) in July 1913 in Death Valley, eastern California, though some experts dispute that measurement and say the real record was 130 F (54.4 C), recorded there in July 2021.

Deaths are starting to mount

In Arizona's Maricopa County, which encompasses Phoenix, there have been at least 13 confirmed heat-related deaths this year, along with more than 160 other deaths suspected of being related to heat that are still under investigation, according to a recent report.

That does not include the death of a 10-year-old boy last week in Phoenix who suffered a "heat-related medical event" while hiking with family at South Mountain Park and Preserve, according to police.

California wildfires fanned by low humidity, high temperatures

In California, crews worked in sweltering conditions to battle a series of wildfires across the state.

In Santa Barbara County, northwest of Los Angeles, the Lake Fire had scorched more than 20 square miles (53 square kilometers) of dry grass, brush and timber after breaking out Friday. There was no containment by Sunday morning. The blaze was burning through mostly uninhabited wildland, but some rural homes were under evacuation orders.

High temperatures were expected in the area through the week, with little relief from the heat even at night.

Festival revelers meet the heat with cold water and shade

At the Waterfront Blues Festival in Portland, Oregon, music fans coped by drinking cold water, seeking shade or freshening up under water misters. Organizers of the weekend revelries also advertised free access to air conditioning in a nearby hotel.

Angelica Quiroz, 31, kept her scarf and hat wet and applied sunscreen.

"Definitely a difference between the shade and the sun," Quiroz said Friday. "But when you're in the sun, it feels like you're cooking."

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