A long-running heatwave that has already broken records, sparked dozens of wildfires and left about 130 million people under a high temperature threat is about to intensify enough that the National Weather Service has deemed it “potentially historic”. The NWS on Saturday reported some type of extreme heat or advisory for nearly 133 million people across the nation – mostly in western states where the triple-digit heat, with temperatures 15 to 30 degrees fahrenheit higher than average, is expected to last into next week. Oppressive heat and humidity could team up to spike temperatures above 100F (about 38C) in parts of the Pacific north-west, the mid-Atlantic and the north-east, said Jacob Asherman, a meteorologist with the NWS. In Oregon, records could be broken in cities including Eugene, Portland and Salem, Asherman said. Dozens of other records throughout the US could fall, Asherman said, causing millions to seek relief from the blanket of heat in cooling centers from Bullhead City, Arizona, to Norfolk, Virginia. “Certainly a pretty anomalous event that we’re expecting here, which looks like it will continue through at least midweek,” Asherman said. At the Waterfront Blues Festival in Portland, Oregon, music fans dealt with heat on Friday by drinking cold water, seeking refuge in the shade or freshening up under water misters. Angela Quiroz, 31, kept her scarf and hat wet and applied sunscreen at she protected herself from the heat at the music festival. “Definitely a difference between the shade and the sun,” Quiroz said. “But when you’re in the sun, it feels like you’re cooking.” On Friday, a new heat record for the day was set in California’s Death Valley – one of the hottest places on Earth. The previous high was shattered by 5F, with the mercury climbing to 127F (53C.) The old mark of 122F was last tied in 2013. More extreme highs are in the near forecast, including 129 F for Sunday at Furnace Creek in Death Valley national park, and then around 130F through Wednesday. The hottest temperature ever officially recorded on Earth was 134F (57C) in Death Valley in July 1913, though some experts dispute that measurement and say the real record was 130F recorded there in July 2021. There was also a record high for the date of 118F in Phoenix, where highs of 115F or hotter were forecast through Wednesday. In Needles, California, where the NWS has records dating to 1888, the high of 122F edged the old mark of 121 F set in 2007. It was 124F in Palm Springs, California. The intense heat – combined with winds and low humidity – means the potential for wildfires to spread is high. Red flag warnings are in effect across much of California until Saturday evening, said the California department of forestry and fire protection, or Cal Fire. Officials urged people to stay vigilant and take extra precautions such as avoiding activities that can spark fires and following evacuation orders. California has more than two dozen wildfires burning across the state, with the two largest, in the central part of the state, burning more than 24,000 acres combined. The Thompson fire, in northern California’s Butte county, has devoured at least 3,700 acres since it was reported on 2 July. By Saturday, the blaze had forced thousands to evacuate and injured two firefighters. It was 71% contained. Cal Fire reported that 26 structures had been destroyed by the blaze. The French fire, which erupted on 4 July near Yosemite national park and quickly grew to more than 900 acres, has held steady as more than 1,000 personnel worked overnight to get it to 25% containment, according to Cal Fire. The eastern US also was bracing for more hot temperatures. Baltimore and other parts of Maryland were under an excessive heat warning, as heat index values could climb to 110F, forecasters said. “Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors,” said a National Weather Service advisory for the Baltimore area. “Young children and pets should never be left unattended in vehicles under any circumstances.” 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 suspected heat deaths still under investigation, according to the county’s most recent report. That does not include the death of a 10-year-old boy earlier this week in Phoenix who suffered a “heat-related medical event” while hiking with family at South Mountain park and preserve, according to police.