News•July 25, 2014

Number of 'Hot Days' Are on the Rise: See Your City

This is the warmest time of year in most of the U.S. And if we continue to pump heat-trapping greenhouse gases into the atmosphere, it’s going to get even warmer — not only in the summer, but throughout the year.

“How warm?” is the obvious question. So we've taken a look at how the number of extremely hot days are projected to increase in a variety of cities by 2050 and 2100 if emissions continue to grow unabated.

How many more extremely hot days will your city get?

The term “extremely hot” means different things in different places, of course. A reading of 100°F is rare in Madison, Wis., but on the other hand, in Phoenix 100°F days are not rare at all. These days, 115°F is considered an extremely hot day there. The mercury matches or tops that scorching number only about once a summer; but by 2100, more than 53 are projected. By contrast, a generally cooler city like Madison gets about 10 days at or above 90°F each year, so the temperature threshold there is lower. By 2100, Madison is expecting more than 67 days of 90°F-plus temps.

The graphic shows your city’s extremely hot threshold: the number of days that temperature is matched/topped on average during the period 1986-2005, and the number times that temperature is expected to be reached/topped by 2050 and by 2100. This assumes there’s no significant cutback in greenhouse-gas emissions.