There's no relief yet from the heat wave that was set over most of the U.S. and made its way to Delaware. The National Weather Service has issued an extreme heat warning for nearly all of Delaware through Wednesday,

The thermometer at Boston Logan International Airport showed 100 degrees as of 2 p.m. Tuesday, according to the National Weather Service’s Boston office. The 100-degree reading ties the record for the hottest ever June temp in city history. It also hit 100 degrees in June 2021, 1952, and 1925.

With a heat wave causing excessive heat warnings in Delaware, you'll hear a lot about the heat index this week. What to know and how to stay cool.