Heat Dome Traps Millions in Extreme Temperatures Across the U.S.

A heat dome is currently impacting over 90 million Americans, leading to extreme temperatures across a wide region. The National Weather Service has issued heat alerts spanning from Nebraska to Florida.

The Mississippi Valley and parts of the Southeast are facing a significant heat threat, expected to persist from Tuesday through at least Thursday. Temperatures are anticipated to exceed 100 degrees Fahrenheit in numerous areas. The heat index, which reflects the "feels-like" temperature, could reach values between 110 and 115 degrees in some locations.

While record-breaking highs are not expected, temperatures are still projected to be significantly above average, approximately 10 to 15 degrees higher than typical for this time of year. The Corn Belt, encompassing parts of the Plains and Central Mississippi Valley, is also expected to experience high humidity, with heat index values potentially reaching 105 to 110 degrees. This phenomenon, known as "corn sweat," occurs as the corn crop perspires under extreme heat, increasing humidity levels.

Overnight lows in the mid-70s to low-80s could potentially break record high minimums in several states, including Alabama, Arkansas, Florida, Georgia, Kentucky, Louisiana, Missouri, South Carolina, and Tennessee. The combination of high humidity and extreme temperatures poses a significant health risk, increasing the likelihood of heat-related illnesses. The lack of overnight relief further exacerbates the threat.

Climate change has increased the likelihood of excessive heat in July, impacting nearly 160 million people in the U.S. A recent analysis indicates that human-caused climate change has made this extreme heat at least five times more likely in certain areas. The analysis uses real-time data to estimate how climate change has increased the likelihood of a particular daily temperature.

In June, a similar heat dome exposed nearly half the country to dangerously high temperatures. Several states broke monthly high-temperature records, with many exceeding triple digits. During that period, one state reported hundreds of people needing medical assistance for heat-related illnesses when the heat index topped 110 degrees in some places.

In response to the increasing frequency of such events, lawmakers have proposed legislation to classify extreme heat as a disaster. This would enable federal funding to be allocated to areas experiencing significant physical and economic distress due to extreme temperatures.