More Dangerous Heat In Wisconsin’s Future: How Hot Will It Get?

MILWAUKEE, WI — Much of Wisconsin, like most of the country, could see a new norm by mid-century when it comes to our sweltering summers and electricity usage for cooling homes, according to new data that calculates temperature extremes associated with climate change.

But how hot will it get? It varies, even just depending on where you are in the greater Milwaukee area —but much of Wisconsin can expect more days with dangerous heat in the future.

Much of Milwaukee County and other Counties closer to Lake Michigan are projected to get around 5-6 days of 100-plus degree Fahrenheit temperatures by 2023, and that could increase to 8-13 days in 30 years, according to data released Monday by the nonprofit First Street Foundation, which helps homeowners calculate property risks due to flooding, wildfires and extreme heat over 30 years, the length of a typical mortgage.

The projections come after an already extreme summer for much of the Milwaukee area, with temperatures reaching near records at multiple points so far in 2022, according to National Weather Service data.

A heat wave in June brought record-confronting temperatures, and two deaths that the Milwaukee County Medical Examiner slated as probable heat deaths.

For Wisconsin, the heat is projected to be higher with great variance depending on how inland you are. By mid-century, portions of Waukesha County, including Brookfield, could be seeing 13 days of dangerous heat. In 2023, much of the Waukesha area is projected to see about 6 days of extreme heat.

The increases also depend on how far north you go in the state, the data showed. Areas like Wasau, Hayward, and Door County are projected to see about 1-3 more days with extreme heat by 2053. Meanwhile, swaths of the state between Madison and Waukesha are projected to see about 16 days of extreme heat by mid-century, the data showed.

Amid the projected rising temperatures, however, Wisconsin appears poised to see fewer extreme days than other parts of the country. In the South, the number of triple-digit days could increase by 20 in places like Texas and Florida could see 70 days of triple-digit heat, analysis by The Washington Post showed.

Conservatively, average temperatures across the United States are expected to increase by 4.5 degrees Fahrenheit over the next 30 years. Also, because hotter temperatures increase the rate of water evaporation, Americans are likely to see warmer, stickier air over the next three decades, according to the First Street model.

Places that already have moist climates, including the Mid-Atlantic and Great Lakes regions, could feel the humidity more acutely, not only during the day, but into the nighttime, according to First Street

“We’re talking about taking summer, which is already hot, and expanding it for months,” Jaime González, director of the Houston Healthy Cities program for the Nature Conservancy in Texas, told The Washington Post. “That’s going to cause all sorts of disruptions to everyday life.”

Also, from the First Street model:

• The most severe temperature changes are expected in Miami-Dade County, which could see an increase from seven days of 103-degree or hotter temperatures to 18 by 2053.

• The number of counties experiencing extreme heat is expected to increase from 50 counties that are home to 8.1 million people in 2023 to 1,023 counties, affecting about 107.6 million people, according to the model. That accounts for about a quarter of the U.S. land mass.

• The so-called “extreme heat belt” situated between the Appalachian and Rocky Mountains stretches from the northern Texas and Louisiana borders to Illinois, Indiana and as far north as Wisconsin. Tens of millions of people living in this region could see heat indices reach 125 degrees by mid-century.
• Some areas expected to see the most dramatic temperature changes are already at the greatest risk for wildfires.