This may not be a surprise to Valley residents dealing with high temps in the upper 90s a week before Halloween, but new research shows more than three quarters of the U.S. population lives in counties with an average of more than nine extreme summer heat days. The data are from 2007 to 2016.

The Natural Resources Defense Council has mapped these extreme days, and with me to talk about what they found is Kim Knowlton, senior scientist and deputy director of the NRDC Science Center.