The dangerously high heat and humidity have prompted several agencies to implement emergency measures.
The National Weather Service says the heat index has pushed past 100 degrees.
Municipalities have been urging elderly residents without air conditioning to go to cooling centers.
Authorities on Long Island say heat appears to be a factor in the death of an 11-year-old girl found in a vehicle with the windows closed.
At the U.S. Open in Queens, an extreme heat policy allows for 10-minute breaks between sets from the heat-absorbing courts.
Temperatures are expected to ease into the 80s on Thursday.
An interactive map locating cooling stations across New York state is posted below.
Cooling Centers Intro to Cooling Centers
Associated Press (C) 2018 contributed to this report.
