A vast heat dome is currently blanketing half of the United States, placing approximately 70 million people under extreme temperature warnings and threatening to set new records. The high-pressure system has settled over at least 15 states, spanning parts of California, Arizona, Nevada, Utah, Colorado, Oregon, Idaho, Montana, Wyoming, New Mexico, Texas, Minnesota, Nebraska, and the Dakotas.
Multiple states, including California, Arizona, Nevada, Utah, and Colorado, have issued widespread extreme heat warnings that are expected to remain in effect through at least Sunday. Some areas may experience record-breaking heat lasting into late next week.
Cities such as Las Vegas and Phoenix are anticipating temperatures to exceed 115 degrees Fahrenheit throughout the weekend, with parts of Southern California potentially reaching 120 degrees. The National Weather Service (NWS) has issued a stern warning about the severity of the heat, advising that car interiors can become lethal within minutes due to rapidly escalating temperatures. The agency cautioned against consuming alcohol or meals high in protein and emphasized avoiding prolonged periods in vehicles.
The heat dome functions by trapping warm, humid air, preventing it from rising and allowing the region to cool. This phenomenon is causing temperatures to soar between 10 and 20 degrees above average for late July and early August. AccuWeather forecasts that Las Vegas could break its daily temperature record for five consecutive days, starting Saturday with an expected high of 117 degrees Fahrenheit. Phoenix is also projected to surpass 115 degrees Fahrenheit on Friday, Saturday, and Sunday, breaking its own heat records.
The NWS highlighted that heat-related illnesses increase significantly during such extreme events and advised taking extra precautions. Recommendations include wearing lightweight and loose-fitting clothing, limiting strenuous activities to early mornings or evenings, and recognizing the symptoms of heat exhaustion and heat stroke. Heat exhaustion symptoms can include heavy sweating, fatigue, cool clammy skin, muscle cramps, dizziness, and headaches. Heat stroke, a more severe and potentially fatal condition that can develop rapidly, may present with a throbbing headache, confusion, nausea, dizziness, and a body temperature above 103 degrees Fahrenheit.
Emergency protocols suggest moving individuals experiencing heat-related distress to a cool, shaded area immediately and calling 911. The NWS noted that elderly adults, children, and individuals with chronic health or mental health conditions are at the highest risk and are urged to remain indoors with air conditioning. Other major cities anticipating severe heat include Los Angeles, San Diego, Salt Lake City, Tucson, and Palm Springs.
For areas where temperatures are expected to reach or exceed 115 degrees Fahrenheit, AccuWeather has warned that most outdoor activities could be dangerous. In addition to heat exhaustion and heat stroke, rapid dehydration and muscle cramps are significant risks for the general population without adequate rest in shade and hydration.
Furthermore, the heat dome is expected to combine with increasing winds in the Northwest, substantially raising the risk of wildfires across several states. AccuWeather meteorologist Chad Merrill indicated that the fire danger could also spread eastward as extremely dry conditions contribute to more ignitions. Prevailing winds are predicted to push smoke towards the Northern Plains, Midwest, Great Lakes, and Northeast throughout August, potentially impacting air quality and even reducing daytime temperatures by obscuring the sun.