Heat wave targeting much of US during July 4 holiday week Parts of the Southeast will see a Heat Index above 100 on Tuesday.

Not unlike the recent heat wave that just engulfed much of Europe, the U.S. Southeast is bracing for triple-digit figures on the Heat Index.

Philadelphia could see highs in the 90s over the next three to four days, as parts of the Midwest have already seen a heat advisory issued for Tuesday. Because of higher humidity, parts of the Southeast are likely to feel like 100 degrees-plus.

The hottest weather on the Fourth of July holiday will stretch from the Gult Coast to the mid-Atlantic, with temperatures in the 90s and more high humidity expected in cities including Atlanta and Washington.