‘Potentially Historic’ Heat Wave Building Across the US West Coast, With No Relief Soon

A map of the United States shows heat advisories in effect for the West Coast on Friday, July 5, 2024. (National Weather Service's Heat.gov website)

A long-lasting, severe heat wave is building up across the West Coast, according to federal weather forecasters on Friday.

Temperatures are expected to reach well above 100 degrees Fahrenheit for many locations on Friday and Saturday. In some places, the temperatures could reach 110 degrees F or greater, and in the desert southwest region, highs of 120 degrees may be possible, say federal forecasters with the National Weather Service in its most recent bulletin.

California, Oregon, Washington, Nevada, and Arizona are bracing for potential wildfires, opening cooling centers and warning residents to stay indoors and keep hydrated as the unrelenting heat wave delivers sweltering temperatures well into the 100s and 110s—with highs in the 120s possible in the Desert Southwest.

Heat watches and warnings were implemented by the federal agency for much of the western United States, according to a map. A running tally operated by the agency shows that more than 150 million Americans are currently under some form of heat advisory on Friday.

“Confidence is increasing that this potentially historic heatwave will last several days,” the National Weather Service’s office in Portland, Oregon, warned in a social media post. It added that the risk of developing heat-related conditions will increase for people across the region.

Specifically, temperatures will rise “into the 100s and 110s over much of California and southern Oregon,” while across much of the West Coast, temperatures will be 15-to-30 degrees above normal, the weather agency said.

“The duration of this heat is also concerning as scorching above average temperatures are forecast to linger into next week,” it added. “Heat impacts can compound over time, therefore it is important to remain weather aware and follow the advice of local officials.”

As a result, the agency warned, people should stay hydrated and away from direct sunlight while in the midst of the heat wave.

Parts of Oregon will experience 100-degree weather on Friday, while the heat could last for about a week with little overnight cooling, said the National Weather Service’s Portland office.

Meanwhile, Multnomah County, which includes Portland, declared a state of emergency for the weekend due to the heat.

“I’m particularly worried about the thousands of people heading to music festivals and sporting events this weekend,” Multnomah County Health Officer Dr. Richard Bruno said in a release. “They’ll be spending a long time outside, may have little access to shade and water, and may not recognize the risk.”

In San Jose, California, an elderly homeless man died earlier this week due to a heat-related illness, the mayor’s office said on social media. Also this week, a 10-year-old child died in Arizona after suffering a heat-related emergency while hiking at a preserve, said the Phoenix Police Department.

The heat wave is occurring as fires continue to burn in northern California, although officials recently allowed thousands of residents who evacuated in Butte County to return on Friday.

The Thompson Fire broke out before noon Tuesday about 70 miles north of Sacramento, sending up a huge plume of smoke that could be seen from space. The fire had burned 5.9 square miles, up from 5.5 square miles earlier Thursday.

Containment of the Thompson Fire near the city of Oroville in Butte County increased to 46 percent on Friday, officials said. But officials warned the hot temperatures could exacerbate the fire or lead to more wildfires.

“The winds are slowly picking up,” said Chris Peterson, information officer for the California Department of Forestry and Fire Protection, or Cal Fire. “You add that with the heat and low humidity,” and the potential for volatile fire behavior grows.

Heat-Related Illnesses

Symptoms of heat stroke include a body temperature of 103 degrees or higher; red, hot, dry, or damp skin; a rapid and strong pulse; nausea, confusion; dizziness; headache, or a loss of consciousness, according to the U.S. Centers for Disease Control and Prevention (CDC) and other health agencies.

People suffering from heat stroke should receive immediate medical attention and 911 should be called, authorities say.

People suffering from heat exhaustion will have cold, pale, and clammy skin; sweating profusely; have a weak and fast pulse; muscle cramps, dizziness; headache, vomiting; nausea; or weakness or tiredness.

As with people suffering from heat stroke, individuals showing signs of heat exhaustion should go to a cool place, have loose clothing, sip water, and if possible, take a cool bath.

The Associated Press contributed to this report.