A dangerous, multi-day heat wave has put more than 100 million people across the U.S. under heat alerts, with at least seven major cities forecast to hit triple digits as the pattern moves from the Southwest and Great Plains toward the Midwest.
Forecasters expect highs of 112 degrees in Las Vegas, 109 in Phoenix and 105 in Rapid City, South Dakota, with Omaha, Denver, Dallas and Kansas City all expected to top 100 degrees and Minneapolis and St. Louis climbing into the upper 90s. High humidity is compounding the danger across a broad swath of the country, with heat index values forecast between 105 and 115 degrees in some areas. Overnight temperatures are offering little relief, with lows only expected to dip to around 90 degrees in Phoenix and Las Vegas.
Extreme heat warnings are currently in effect for Phoenix, Las Vegas, Minneapolis, Memphis, Omaha and parts of Missouri, among other locations. The National Weather Service has cautioned that the extended exposure without meaningful overnight cooling raises the risk of heat-related illness, particularly for people without reliable access to air conditioning.
This marks the second major heat wave to hit large parts of the country in less than a month, following a record-breaking stretch around the Fourth of July that set numerous all-time highs, including a 109-degree reading in Salt Lake City and a peak of 106 degrees in Atlantic City. A cold front is expected to begin bringing relief to the Upper Midwest early this week, though the timeline for the rest of the affected region remains less clear.