The death toll in New Jersey from a days-long heat wave that gripped much of the East Coast during the Fourth of July weekend may be as high as 29, the state’s Department of Health said on Monday.

Those who died ranged in age from their mid-30s to their 80s, and most of the deaths occurred in New Jersey’s densely populated central and northern regions, where temperatures exceeded 100 degrees for days and remained exceptionally warm even after the sun set, state officials said.

“This was crazy heat,” said Dalya Ewais, a health department spokeswoman. “This was not your normal heat wave.”

Pathologists must still confirm that hyperthermia — heat stroke and heat exhaustion are severe forms — caused each of the deaths linked to the extreme heat. But Ms. Ewais said that state officials decided to release the number of likely heat-related fatalities as a reminder of the risks posed by extended exposure to high temperatures, among the leading causes of weather-related deaths.

State officials said that the people who had died were found in homes, cars and outdoors.

With the heat came wind, then rain. Wind gusts reached 71 miles per hour on Friday evening, just shy of hurricane strength, downing tree limbs and toppling power lines. Then, on Monday morning, intense rainstorms pelted parts of South Jersey. Cars were submerged by flash flooding in Monmouth County, and the roof of a BJ’s Wholesale Club in Ocean County partially collapsed. Shoppers and security cameras recorded video as the ceiling began to cascade downward, but no injuries were reported.

About 185,000 homes and businesses across Connecticut, New Jersey, New York and Pennsylvania remained without power late Monday afternoon, according to poweroutage.us, which tracks data from utility companies.

The number of potentially health-related fatalities linked to the scorching weather in New Jersey comes close to the grim toll recorded during Hurricane Sandy and Hurricane Ida, two of the deadliest natural disasters in New Jersey’s recent history. (At least 40 deaths were attributed to Sandy’s devastation in 2012; in 2021, 30 people died after Ida caused flash flooding throughout much of New Jersey.)

The state’s climatologist, John Krasting, of Rutgers University, said a high-pressure system had created a dome-like effect that trapped heat and air pollution and also stalled Monday’s storm from moving offshore more quickly. On land, more than four inches of rain fell rapidly in parts of New Jersey, swamping cars as roads turned to rivers along parts of the Jersey Shore.

Dr. Krasting, a former researcher for the National Oceanic and Atmospheric Administration, said that climate change and a two-year drought in New Jersey, which had left the soil unprepared to rapidly absorb rain, contributed to the intensity of the week’s weather.

“Our changing climate,” he said, “is changing the likelihood of extreme events like this.”

Last week, New Jersey’s governor, Mikie Sherrill, had warned residents to brace for the “hottest stretch we’ve seen in 14 years.”

After at least 19 deaths had been linked to the heat, Ms. Sherrill held a second weather-related news conference on Saturday. She and the state’s health commissioner, Dr. Raynard Washington, reminded residents about how to find cooling centers and other heat-related information.

“Unfortunately, many of these individuals were found in homes without air-conditioning,” Dr. Washington said on Saturday.

Officials in New York City have so far confirmed that three people died from heat-related illnesses; all three died in their homes. The victims, whom the medical examiner’s office did not identify, each had underlying conditions. According to the medical examiner’s office, all three had cardiovascular disease and two had diabetes.

New York officials did not indicate how many other deaths were suspected of being tied to the high temperatures as hospitals treated an unusual number of patients for heat-related problems.

On Friday, when temperatures hit triple digits in parts of New York for the second day in a row, emergency rooms across the city logged 146 visits for heat-related illness. That was the highest number of heat-related visits recorded in a single day in recent years.

The day before was the hottest day in the city in more than a decade. Emergency rooms logged 100 heat-related visits that day. Since 2017, emergency rooms have logged 100 or more heat-related visits on only six days, according to data provided by New York City.

It was much the same story in New Jersey. On Thursday, 99 people were treated in New Jersey hospitals for heat-related emergencies, according to the state’s health department dashboard. The next day, 132 people sought treatment.

Throughout the heat wave, nighttime temperatures had remained unusually high, giving residents almost no break from the oppressive heat until temperatures began to fall on Sunday.

In Newark, New Jersey’s largest city, the coolest recorded temperature at the airport on Thursday night into Friday was 87 degrees, Dr. Krasting said.

That was two degrees shy of the warmest night ever since the state began keeping records in the 1890s.

For now, Hammonton, N.J., where readings dropped only to 89 degrees on June 26, 1952, continues to hold the record.

“Our bodies are used to recovering when the temperatures drop at night,” Dr. Krasting said. “That didn’t happen.”

Maria Cramer contributed reporting.