 Over 60 million Americans under severe thunderstorm watches from North Carolina to Maine amid record-breaking July 4th travel. Over 1,100 flights have been canceled this evening in the U.S., according to FlightAware. Most are due to storms. ABC News forecaster Danny Beckstrom. While the Northeast is stormy, the South is steamy. The southern half of the country settling into a stretch of scorching heat through the 4th of July. We're talking triple-digit heat indices for places like Houston, Tulsa, and New Orleans.