The man, 78, who was not identified, died of hyperthermia on July 19, when temperatures reached a high of 95 degrees, the Medical Examiner's office said Sunday.
Hyperthermia occurs when a body has an elevated temperature and its heat-regulation systems fail, which can lead to death, according to the U.S. Department of Health.
The ME's office did not provide the man's address, but according to the National Weather Service, Friday was one of the final days of the week's heat wave, which began to taper off with a brief high of 92 on Saturday, and a short stint at 88 degrees on Sunday.
The only other heat-related death so far this summer took place July 8 in Staten Island.
The official cause of death was hyperthermia due to elevated environmental temperatures.