Forecasters said relief was on the way, with an approaching cold front expected to bring thunderstorms into the region Thursday night and return temperatures to more seasonable levels by Friday.
Readings of 101 degrees were recorded just before 2 p.m. at Newark Liberty International Airport and Atlantic City International Airport in Pomona. That shattered the previous marks of 99 degrees for Newark and 98 degrees for Atlantic City. Both were set in 2008.
Most other areas of the state were in the upper 90s for a second straight day, and the heat index in most areas ranged from 100 to 107 on Thursday.
Residents were urged to stay in air-conditioned or cool areas, drink lots of water and check on elderly relatives and neighbors.
But not everyone could follow that advice.
"I'd love to be indoors, but I don't make any money that way," said Jose Serrano, part of a landscaping team that was cutting lawns and trimming bushes at a Toms River town home complex Thursday morning. "When it comes to working in these conditions, you just do what you have to do, you know?"
Serrano and his co-workers were constantly drinking water and sports drinks, and taking turns working in shaded areas. They also took frequent short breaks, part of their plan to avoid heat stroke and other heat-related illnesses.
"We've all been doing this type of work for years, so we know what we need to do and we do it. And we all keep watch on each other to make sure everyone stays OK," Serrano said.
While no weather-related deaths had been reported as of Thursday afternoon, the heat was taking its toll.
Hospitals reported treating numerous patients with heat-related illnesses, though most cases were considered "minor." And emergency rooms also were seeing an increase in patients with chronic diseases, whose conditions can worsen under the added stress of high temperatures and high humidity.
Among the more serious cases was a 93-year-old man who was in critical condition Thursday at St. Joseph's Hospital in Paterson with heat stroke.
Mark Rosenberg, a physician who runs the emergency department at St. Joseph's, was bracing for more patients on Thursday.
"Usually the second day of a heat wave is much worse," Rosenberg said.
Several cities opened cooling centers for residents, and dozens of school districts without air-conditioned buildings dismissed students early.
Associated Press Writer Josh Lederman in Trenton contributed to this report.