America could see a new 'extreme heat belt' by 2053

An area of intensely warm weather -- a so-called "extreme heat belt" -- with at least one day per year in which the heat index hits 125 Fahrenheit (52C), is expected to cover a US region home to more than 100 million people by the year 2053, according to a new study. The research, carried out by nonprofit First Street Foundation, used a peer-reviewed model built with public and third-party data to estimate heat risk at what they called a "hyper-local" scale of 30 square meters. First Street Foundation's mission is to make climate risk modeling accessible to the public, government and industry representatives, such as real estate investors and insurers. The biggest predicted shift in local temperature occurred in Miami-Dade County, Florida, which currently sees seven days per year at its hottest temperature of 103 Fahrenheit. By 2053, that number is expected to increase to 34 days at 103 degrees.

A key finding from the study was that heat exceeding the threshold of the National Weather Service's highest category -- called "Extreme Danger," or above 125F -- was expected to impact 8.1 million people in 2023 and grow to 107 million people in 2053, a 13-fold increase. This would encompass a geographic region stretching from northern Texas and Louisiana to Illinois, Indiana, and Wisconsin -- inland areas far from the more temperate weather often seen near the coasts. Heat index, also known as the apparent temperature, is what the outside temperature really feels like to the human body when relative humidity is combined with air temperature. To create their model, the research team examined satellite-derived land surface temperatures and air temperatures between 2014 and 2020, to help understand the exact relationship between the two measurements.This information was further studied by factoring in elevation, how water is absorbed in the area, the distance to surface water and the distance to a coast.