Hang onto your hats and grab an umbrella if you live anywhere in the northeastern United States.
Severe thunderstorms with damaging wind gusts are in the forecast for later Tuesday that could affect some 51 million Americans in Boston, New York City, Philadelphia and Pittsburgh, NBC meteorologist Bill Karins said.
Travelers flying out of New York, Philadelphia and Washington are advised to plan for possible delays as the storms blow through, The Weather Channel warned.
The stormy weather also brings with it the threat of tornadoes in and around Albany, New York, Karins said.
Meanwhile, the high heat and humidity that has blanketed the region for days shows no sign of letting up with highs in the 90s and an afternoon heat index above 100 degrees across much of the mid-Atlantic, Karins said.
Things are expected to start cooling off a bit towards the weekend — but only a bit, said Karins.
Meanwhile, flash flood watches remain in place from the coast of Texas all the way north to the Ohio River Valley, the National Weather Service reported.