Deadly heat wave shatters temperature records in the West: Who is it affecting and when will it break?

A dangerous heat wave has shattered temperature records in the Western United States this week, triggered heat warnings and advisories for millions of people, caused at least five deaths and left dozens of others hospitalized.

Who has been affected?

According to the National Weather Service, about 36 million people, or approximately 10% of the U.S. population, were under an excessive-heat warning on Monday. And more than 146 million people were under extreme-heat advisories, watches or warnings.

In Oregon, blistering heat was suspected in at least four deaths between Friday and Monday in the Portland area. According to Multnomah County health officials, three of the victims, all men, were found dead outside. Another 33-year-old man who was transported to a Portland hospital died from a suspected heat-related illness.

In Nevada, the high temperature in Las Vegas on Sunday hit a record 120 degrees. Nearly two dozen people were treated at a local burn center for pavement burns last month; others continue to be admitted on a daily basis, Dr. Syed Saquib, director of University Medical Center's Lions Burn Care Center, told KVVU-TV. The pavement can be up to 40 degrees warmer than the air and can cause second-degree burns in a matter of seconds, Saquib said.

In Arizona, Phoenix set a new daily record for the warmest low temperature ever: It never got below 92 degrees. And heat-related deaths in the Phoenix area have been mounting. In Maricopa County, which encompasses Phoenix, there have been at least 13 confirmed heat-related deaths this year, according to the Associated Press. More than 160 additional deaths suspected of being related to heat are still under investigation.

And in California, a motorcyclist died over the weekend from heat exposure in Death Valley National Park, where temperatures reached a record 127 degrees on Friday, 128 on Saturday and 129 on Sunday. Another was treated for severe heat illness. Tourists from around the world are still drawn to the park in the summer to experience the extreme heat, despite the risks.“While this is a very exciting time to experience potential world-record-setting temperatures in Death Valley,” Mike Reynolds, the park’s superintendent, said in a statement, “we encourage visitors to choose their activities carefully, avoiding prolonged periods of time outside of an air-conditioned vehicle or building when temperatures are this high."

How long will this heat wave last?

The current heat wave impacting millions of people in the West is persistent and shows no signs of dissipating.

Excessive-heat warnings remain in effect through the rest of the week in most western states, with more record high temperatures expected.

"No let-up expected to the string of record high temperatures being set across large portions of the West," the National Weather Service said. "The mid- to upper-level high that has been anchoring the record heat in the West is not expected to change much over the next several days, as it remains locked in place, stretching from Southern California/Desert Southwest, northward through the Great Basin and across the Pacific Northwest and Northern Rockies."

Excessive-heat warnings, watches and heat advisories are currently in effect for nearly all of Washington state, Oregon, California, Idaho, Nevada and western Arizona.

"Numerous record high temperatures are expected across these areas over the next few days, where high temperatures will be anywhere from 10 to as high as 30 degrees above average," the weather service added. "In addition to the record-high daily temperatures, the early-morning lows are also expected to set records across large portions of the West over the coming two mornings. The multi-day length and record warm overnight temperatures will continue to cause heat stress to anyone without adequate cooling and hydration."

In the meantime, forecasters are urging people to drink plenty of fluids, take extra precautions when outside, take frequent air-conditioning breaks when possible, check up on relatives and neighbors, and not leave young children and pets in unattended vehicles.

“Car interiors will reach lethal temperatures in a matter of minutes,” the weather service said. “Young children and pets should never be left unattended in vehicles under any circumstances.”