New York City is sweltering through its second heat wave of the summer.

The threshold for what constitutes a heat wave varies by region, but here in the NYC area it is defined as three consecutive days with temperatures reaching 90°F or higher. Wednesday marked the city’s fourth day of scorching conditions.

With the dew point temperature in the 70s, it felt even hotter. The heat index – the so-called real feel temperature – reached into the triple digits.

The main driver of this dramatic heat and humidity is a dominant Bermuda High, a large area of high pressure situated off the east coast. Spinning clockwise, it has been steering hot, humid air from the Gulf of Mexico toward the northeast.

While these conditions are oppressive, they can also be dangerous. The NWS issued both heat advisories and air quality alerts for the city over the past few days.

The normal high for this time of year in the Big Apple is 84°F.

Credit: The Weather Gamut