FILE - Hunter Van Dyne pauses to wipe sweat from his forehead inside a hot fireworks tent as he works to set up for the opening of Powder Monkey Fireworks, in Weldon Spring, Mo., Monday, June 17, 2024. While a heat wave brings the hottest temperatures so far this year to the Midwest and Northeast, forecasters also are discussing heat domes. What's the difference? A heat dome forms when high pressure in the upper atmosphere causes the air below it to sink, heat up and expand. (AP Photo/Jeff Roberson, File)