LOS BANOS, Calif. — It was 109 degrees — and counting — at the local Merced County Library branch early Saturday afternoon, a designated cooling center where people were beginning to show up to escape the heat.

“Too hot,” said Alandra Lara, 38, the librarian on duty. “A blast furnace, once you step out of the air conditioning.”

The massive heat wave sweeping the West has blanketed millions of Americans in triple-digit temperatures, leaving cities, hospitals and residents struggling to cope with the extreme highs. By late afternoon Saturday, temperatures had spiked to 111 degrees in Phoenix and 126 degrees in Death Valley, Calif. Las Vegas tied its all-time record of 117 degrees.

The latest round of scorching temperatures isn’t unfamiliar, as the last few weeks have been filled with extreme heat. The country last month had its hottest June on record, with an average temperature of nearly 73 degrees in the contiguous United States, exceeding the 2016 record by about 1 degree, according to the National Oceanic and Atmospheric Administration. Eight states, including Arizona, California and Idaho, reported their hottest June in 127 years of record-keeping.

In all, the country has weathered eight “billion-dollar” climate calamities so far this year, according to NOAA. They include the ongoing drought and heat waves in the West, as well as April hailstorms in Texas and May flooding in Louisiana. Last week, a “thousand-year” heat wave killed hundreds of people in the Pacific Northwest and British Columbia, Canada.

“We now have multiple crises within crises: a covid-19 pandemic, historic wildfires that left us with some of the worst air quality on the planet, a historic ice storm in February, and now a mass casualty event from heat,” said Jennifer Vines, health officer for Multnomah County, which includes Portland, Ore. “We are looking at this changing climate as a glimpse of the new normal.”

Washington state on Friday announced emergency measures to protect those who work outdoors by mandating access to sufficient shade and cool drinking water as well as breaks every two hours when the temperature exceeds 100 degrees. Oregon passed similar rules a day earlier.

“The heat experienced in our state this year has reached catastrophic levels,” Washington Gov. Jay Inslee (D) said in a statement. “The physical risk to individuals is significant, in particular those whose occupations have them outdoors all day.”

Emergency rooms in the West are reporting an uptick in heat-related illnesses and deaths. Doctors say older Americans and the homeless are among the most vulnerable to extreme temperatures. The risk, they say, is particularly acute this year, given rising rates of homelessness during the coronavirus pandemic.

“We’re still seeing lingering impacts from a huge heat surge at the end of June,” said Steve Mitchell, medical director of Harborview Medical Center Emergency Department in Seattle. “And it’s not just temperature-related illnesses. The heat also makes everything else worse: lung conditions, heart conditions, especially for older adults."

Case workers for Phoenix Rescue Mission, which supports the local homeless population, have been offering cold water and rides to heat relief centers to people and families on the streets.

“This heat wave is significant because it’s one of many we’ve already had this summer,” spokesman Ryan Brown said. “When you have heat wave after heat wave, it really adds up and gets really dangerous.”

Gov. Gavin Newsom (D) this week urged residents and businesses in California to reduce their energy consumption as the state battles high temperatures and rapidly growing wildfires. The state’s power grid operator has asked residents to set their thermostats to at least 78 degrees, avoid using major appliances and turn off unnecessary lights.

The mercury had already hit 99 degrees by 10:15 on Saturday morning in California’s Central Valley.

James Schmidt sat in his car parked in the shade of dense trees and shrubs, sipping from a plastic bottle on the Old La Grange Road bridge over the Tuolumne River, which, like many nearby rivers and streams, is lower than usual because of extreme drought. The 27-year-old, who is a carpenter for a construction company in Modesto, says it’s been too hot to work.

“There’s nothing to do but sit in the house and be miserable,” he said.

He drove to the river hoping to cool down with a swim. He walked out on the shadeless truss bridge and looked down at the shallow water. He said in summers past, he has jumped from the highest beams on the bridge. On this day he decided against jumping at all.

Mark Kreidler reported from Sacramento, and Guy McCarthy from Waterford, Calif. Matthew Cappucci contributed to this report.