Mid-summer heat and humidity continues today as we will warm up to the upper 80s this afternoon after a morning low of only 77 degrees. A stationary front is camped out more or less along I-90 north of the city, allowing warm, moist, air to drift northward from the Gulf of Mexico. Under these conditions it won't take much of an upper-level disturbance to produce showers or thunderstorms. It is difficult to pinpoint exactly where the storms will form, so Manhattanhenge may or may not be visible, but any storms that do form could produce heavy rainfall and localized flooding.
Tomorrow is expected to be even warmer and more humid. Look for a high in the lower 90s and oppressive amounts of humidity in the city and northeastern New Jersey. The beaches will be a bit cooler but there won't be any escaping the humidity. The extra heat and moisture will likely produce another round of showers and thunderstorms tomorrow. With the added oomph some storms could be severe, with gusty winds and heavy rainfall.
The stationary front is expected to start moving southward later on Thursday. That will bring a good chance of widespread rain starting tomorrow night and lasting well into Friday. It also means cooler weather! Temperatures on Friday will stay in the mid 70s under overcast, rainy skies and a northeasterly wind. After the front passes somewhat drier weather will be in place for the weekend.