A dangerous heat wave is expanding into new areas of the West and lingering in others Friday, bringing with it record-breaking temperatures and a serious risk of heat-related illness.
The searing heat has already taken its toll. Since last weekend, multiple people in different parts of the US have died or have been hospitalized due to heat-related illnesses.
The worst of the heat peaked Thursday for much of California and the Southwest, but unseasonably hot conditions will stick around in these areas and expand into the Pacific Northwest at least through the weekend.
Heat alerts are in effect for more than 16 million people in California, Nevada, Arizona, Utah and New Mexico. Most will last through Friday but alerts in Las Vegas and Death Valley, California, last into Saturday.
Several notable temperature records were broken Thursday in California, Arizona and Nevada.
In California, a high of 122 degrees in Death Valley broke a daily record set in 1996. And in Fresno, a 121-year-old record was tied Thursday when the city maxed out at 107 degrees.
Phoenix recorded its first high of 110 degrees or more this year when thermometers topped out at a daily record-setting 113 degrees Thursday.
Las Vegas soared to 111 degrees Thursday, the earliest in the year the city has reached the mark, breaking the daily record of 110 degrees set in 2010.
View this interactive content on CNN.comSeveral people across US have died from heat-related illnesses
Six people believed to be migrants have died because of the heat in the past week along the US-Mexico border from southwestern Texas to New Mexico, according to US Border Patrol and the Sunland Park, New Mexico, fire department.
Four people died “from heat stroke and dehydration” while triple-digit temperatures baked the area last weekend, the US Border Patrol, El Paso Sector said. Two more people were discovered in a desert area about six miles from the border in Sunland Park and were pronounced dead Wednesday, Sunland Park fire chief Daniel Medrano told CNN.
Sunland Park is around 10 miles northwest of El Paso, Texas, along the New Mexico-Mexico border.
Excessive heat is the leading weather related killer in the US, according to the National Weather Service.
“This is especially true in the urban centers, where population density, the urban heat island, and building construction exacerbate the effects of excessive heat,” the weather service says. “A combination of high heat and humidity can lead to heat related illness, including heat cramps, heat exhaustion, and heat stroke.”
In the East, a 59-year-old man died of heat-related complications in Prince George’s County, Maryland, officials said Wednesday. Additional details about the man’s death, which was the state’s first heat-related death of the year, were not released.
Heat proved challenging for firefighters battling a blaze in California’s Napa County Wednesday. Four firefighters were sent to area hospitals for injuries related to difficult terrain and “hot summer conditions,” according to CAL Fire’s Sonoma-Lake-Napa Unit. All four are expected to make full recoveries.
Phoenix emergency responders on Thursday say they hospitalized 11 people due to heat exhaustion while they were attending a Donald Trump rally at the Dream City Church.
With the risk of heat-related illnesses increasing for millions across the country, officials in several states are trying to keep residents safe during the smoldering heat. In California, cooling centers have been set up for those affected by triple-digit heat. As Texas contends with both severe storms and excessive heat, a state disaster declaration remains active.
View this interactive content on CNN.comHazardous heat expected into weekend
Heat will continue through the weekend before easing off a bit early next week. However, many typically hot areas in the West will still have to contend with temperatures up to 10 degrees above normal and warm nighttime lows will make it difficult for those vulnerable to extreme conditions to be able to cool off.
The Las Vegas metro area is at “extreme” risk from the heat through Saturday, according to a scale from the National Weather Service that gauges heat’s potential impact on people’s health. The highest level on the heat risk scale means residents without enough cooling and hydration will be impacted, and “impacts are likely in most health systems, heat-sensitive industries and infrastructure.”
Several more large metro areas in Arizona, California, New Mexico and Texas will face a “major” Level 3 of 4 heat risk.
Summerlike heat will expand north and east Friday and reach the Northwest and parts of the Rockies. Records could be broken in parts of Oregon, Washington and Idaho from Friday through the weekend.
While it won’t be record-breaking, Seattle could come close to 80 degrees on Saturday, 10 degrees warmer than what’s typical for early June.
CNN’s Mary Gilbert, Andy Rose and Joe Sutton contributed to this report.