Wthr Weather turned dangerous across parts of the United States this week, with more than 39 million people under heat alerts as temperatures climbed and some areas were expected to see heat index values near 120°F.
The National Weather Service said more than 3.5 million people in southern Arizona, the lower Rio Grande Valley in Texas and southern New Mexico faced the highest heat risk level, while 43.4 million more were in a major risk zone. Those levels were described as dangerous for anyone without adequate cooling or hydration.
Arizona, California and Nevada
A heat dome that had already brought extreme heat to the central and eastern U.S. shifted west and was expected to intensify before spreading into the intermountain West and northern High Plains this weekend. On Friday, extreme heat warnings covered parts of Arizona, California, Nevada, Utah, Oklahoma and western Arkansas, including Phoenix and Tucson, Las Vegas, Death Valley, Joshua Tree National Park, Zion National Park, Capitol Reef National Park and the Lake Powell area in Utah.
A high of 119°F was recorded Thursday at weather stations near Topock, Ariz., on the California border, and near Tecopa, Calif., in the Mojave Desert southwest of Death Valley National Park. In parts of the Southwest, highs were forecast to range from around 100°F to as high as 120°F in some desert locations, and some places were expected to log one of their 10 hottest days on record.
Sunday and Monday night
Most warnings were expected to remain in effect through Sunday, and parts of California's Mojave Desert, the Coachella Valley and parts of Arizona were expected to stay under extreme heat warnings through Monday night. Heat index values were forecast to reach as high as 120°F in parts of southern Arizona and South Texas on Sunday.
Overnight lows were expected to stay in the upper 70s and low 80s across much of the Gulf Coast, while temperatures in desert cities were expected to remain well above 80°F overnight. That leaves little recovery time between hot days.
National Weather Service HeatRisk
The National Weather Service advised people to drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. It also said to take extra precautions when outside, wear lightweight and loose-fitting clothing, limit strenuous activities to early morning or evening, and take action when symptoms of heat exhaustion and heat stroke appear.
For anyone in the warning area, the practical move is to treat the next few days as an endurance test: stay cooled, keep activity low in the hottest hours, and watch for the areas where the warnings last longest, because those are the places least likely to get relief before Monday night.
