"Dangerous" heat days in Miami will nearly double by 2053, study says

If Miami summers feel hot now, new research predicts that our days of extreme heat will skyrocket in the coming decades.

Driving the news: Miami-Dade leads the nation in counties that will see the biggest jump in so-called dangerous days, when the heat index passes 100°F, by 2053, according to a nationwide study by the nonprofit First Street Foundation.

• Broward and Palm Beach counties are close behind.

Why it matters: Extreme heat is the leading weather-related killer in the U.S. In Miami-Dade, rising heat indexes are increasing residents' risk of heat-related illnesses and even death, according to a county heat study.

• Miami-Dade has more than 100,000 outdoor workers, more than any other county in Florida, according to the Miami Herald.

What they're saying: Understanding future heat risks can help local communities make more informed decisions about how to protect their health and properties, the First Street study's authors write.

Zoom in: Miamians will experience about 40 extra days where the heat index is over 100 degrees – from about 50 days in 2023 to 91 days in 2053 – according to the study.

Of note: The heat index — known as the "feels like" temperature — factors in temperature and relative humidity.

The big picture: In the coming decades, climate change will cause the Lower 48 states to be a far hotter and more precarious place to be during the summer, Axios' Andrew Freedman writes.

• Conservative estimates say the average temperature will increase by 2.5 degrees across the U.S. in the next 30 years.

The extremes: The study projects that "extreme danger" events — when heat indexes pass 125°F — will impact 107 million people across the U.S. in 2053, an increase of 13 times over 30 years.

• These extremely high heat indexes are projected to be concentrated in an "extreme heat belt," which would stretch north from Texas and Louisiana through Iowa, Indiana and Illinois.