It's the kind of heat wave that causes the minutes to tick by at an agonizing pace as you stand on the subway platform, where it feels even worse than it does outside.
NBC New York went out to measure just how much hotter it can be underground.
At the 72nd and Broadway station on the No. 1, 2 and 3 line, it was 92 degrees outside, just before noon.
Down below, in the depths of the station, the temperature read 100.
Over at the 168th Street station, the elevator descending to the balmy basement was a steamy 95 degrees.
"It feels like you're just stepping outside of a fire," said straphanger Steven Gist. "All the heat, it's unbreathable."
Meanwhile the heat and humidity that have gripped the tri-state for the last few days continue, with the most stifling temperatures still to come.
Temperatures soared into the 90s in many areas on Tuesday. It was the fourth day of an official heat wave, achieved when temps hit 90 or above for three or more days in a row.
On Wednesday, the humidity will build through the day with sunshine and temperatures near 90 degrees again. The heat wave begins to peak Thursday.
Friday looks to be the worst day for heat with scorching temperatures near 100 degrees.
The heat wave is likely to continue into the weekend and may not break until early next week.
In New Jersey, the National Weather Service has issued an excessive heat warning is in effect from noon Wednesday until 8 p.m. Friday for Mercer, Gloucester, Camden and northwest Burlington counties.
An excessive heat watch covers the rest of the state.
The state's largest utility expects to have no problem delivering additional power. PSE&G has crews for service interruptions.
Drink plenty of water, limit time outside and take care of pets.
As always, check back with NBC New York for the latest weather information, including severe alerts, video forecasts and interactive radar.