Heat, high humidity to spur locally heavy storms in northeastern US

Hot and humid conditions over a large part of the Northeast will be accompanied by locally heavy, gusty thunderstorms in the coming days.

The core of the heat and high humidity will be focused over the mid-Atlantic and appropriate for the middle of July into Thursday. Meanwhile, cooler-than-average temperatures will hold over the northern tier for a time, before pushing southward.

Temperatures will climb into the 90s F and may approach 100 in parts of Virginia, Maryland, Delaware, southern New Jersey and southeastern Pennsylvania through Thursday.

AccuWeather RealFeel® Temperatures will top 100 in the core of the hot air.

These conditions will make strenuous activity difficult, if not dangerous, during the hottest part of the day.

Across the northern tier, highs will range from the upper 60s to the upper 70s.

The temperature contrast will likely not sit well with the atmosphere.

“The fuel for sustained and repeated thunderstorm activity is heat and moisture," according to AccuWeather Senior Meteorologist Matt Rinde.

"The Northeast is currently being fed plenty of moisture, while heat also continues to build slowly northward,” Rinde said.

As a hot and humid air mass engulfed much of the region early this week, many may have guessed from experience that wetter weather is on the way.

“The region is being primed for thunderstorm development,” said Rinde.

As a result, daily, widespread showers and storms are expected to fire throughout New England, the central Appalachians and the upper part of the mid-Atlantic, through Friday.

Storms through Thursday afternoon will tend to be spotty in nature farther south. However, multiple showers and thunderstorms will occur from late Thursday through Friday over much of the mid-Atlantic as the cooler air to the north begins to advance southward.

Beachgoers and others enjoying the heat and sunshine should move indoors at the first sign of threatening weather to avoid injury by lightning or wind-blown debris.

While many of these storms will do little more than interrupt outdoor activities in the Northeast, some could be strong enough to flood roads or cause localized power outages.

“Each passing storm could bring drenching rainfall and even a few strong wind gusts,” warned Rinde.

The cooler air is expected to settle into the hottest areas of the region this weekend, potentially dropping high temperatures by up to 15 degrees from Thursday's peak.