The National Weather Service has warned of "searing heat and oppressive humidity that occurs during the 'dog days of summer'.

It’s the hottest time of the year in the United States and another heat dome is about to make millions of people feel every bit of it.

"The logical next step was to find where it might be in the United States." The map and an accompanying report detailing the results were published Thursday (Jan. 16) on the USGS website.