What to Know About This Week’s Heat Wave in New York

Millions of Americans are in store for a major heat wave this week as temperatures climb in the Northeast and other regions of the country, marking the kickoff to a summer that will be hotter than usual. In New York City, temperatures will be in the high 90s.

Climate change means temperatures are climbing earlier in the year, and dangerous heat is occurring more frequently. Prolonged exposure to hot temperatures can cause severe health consequences and even death.

Here’s what to know in order to stay safe and cool.

How hot will it get in New York City?

Forecasts show that temperatures will start to climb in New York City on Tuesday and remain elevated throughout the week, with a potential peak of 96 degrees on Friday.

The heat index is a measure of how hot it really feels outside, taking into account humidity and temperature. The heat index forecast for Friday is 98 degrees Fahrenheit.

Mayor Eric Adams said in a statement that he would activate the city’s heat emergency plan starting on Tuesday.

“The first heat wave of the season is here, and New York City has a plan to beat the heat — but we want all New Yorkers to have a plan as well,” Mr. Adams said. “A heat wave can be more than just uncomfortable, it can be deadly and life threatening if you are not prepared.”

When the plan goes into effect, the city will open hundreds of cooling centers — air-conditioned indoor facilities that can be used during the day. The Fire Department will turn some hydrants into sprinklers by installing spray caps. And city officials will work closely with the National Weather Service to monitor forecasts and communicate changes to the public.

Approximately 350 people die on average each summer in New York because of hot weather. Black New Yorkers are disproportionately affected and more likely to die from heat stress than others.

More than half of those who die each year live in homes without air-conditioning, according to Dr. Ashwin Vasan, the city’s health commissioner.

How can I find places to cool off?

Though libraries are traditionally among the most popular cooling centers available to New Yorkers, the city’s public libraries have been closed on Sundays since late last year, when Mr. Adams announced budget cuts.

“New York City’s libraries are steadfast partners for our city in times of need,” Sandee Roston, a spokeswoman for the New York Public Library, said in a statement on behalf of the city’s three library systems. She said the libraries would push to have budget cuts restored “in hopes that we can once again open our doors to New Yorkers seven days a week.”

Which neighborhoods are most at risk?

While extreme heat will affect the entire city, some neighborhoods are more at risk of experiencing dangerous conditions than others.

The city’s Heat Vulnerability Index — an effort spearheaded by the health department in conjunction with Columbia University — analyzes the neighborhoods that face the most danger during a heat wave.

These areas often have higher surface temperatures, fewer green spaces and less access to air-conditioning. They have more Black residents and residents with lower incomes.

The index shows that many of those neighborhoods are in the Bronx, Brooklyn and Queens.

A stretch of the Bronx running from Mott Haven to Fordham Heights is one of many areas in the borough to score a 5, meaning residents are at the highest risk of suffering from extreme heat. Eastchester and Williamsbridge are among other neighborhoods that face that level of risk.

In Queens, some of the neighborhoods facing heightened levels of risk include Jamaica, Hollis and St. Albans.

In Brooklyn, high-risk neighborhoods include Brownsville, East Flatbush and East New York.

Is extreme heat more dangerous for some people than others?

Adults who are 65 or older, children under 5, pregnant women and people with chronic medical conditions including heart conditions and diabetes are more vulnerable to extreme heat, according to the Department of Health and Human Services.

Homeless people can be among those most affected by heat. They might not have access to the air-conditioned refuges that are available to other New Yorkers, said Brian Ourien, the communications director of the Bowery Mission, a prominent aid group.

“Air-conditioning at this point becomes a necessary part of our lives on days that are extremely hot, and we can’t emphasize enough how people should be indoors during times like these because it’s risky for them,” Mr. Ourien said.

Zach Iscol, the city’s emergency management commissioner, said the department issues a Code Red during periods of extreme heat, during which outreach teams help homeless people get to shelters and cooling centers.

The Office of Emergency Management is also piloting a program to give outdoor workers and day laborers cooling kits.

In a statement, Dr. Vasan urged New Yorkers to look out for others.

“Take care of one another by checking in on family, friends and neighbors — especially older adults — to make sure they have a plan to keep cool and beat the heat,” he said.

How will the city’s power grid fare?

Millions of New Yorkers trying to beat the heat this week will crank up their air- conditioners and run fans without pause for days at a time. Electricity usage can double during especially hot stretches of the summer, pushing the city’s power grid to its limit.

This is the first heat wave of the summer, and some outages are likely, said Patrick McHugh, the senior vice president of electric operations at Con Ed. Parts of the grid that have degraded or broken since last summer will get their first true test of the year, and Mr. McHugh expects some of them to fail.

The utility is prepared to fix those weak spots as needed, and it has beefed up staffing in call centers and repair teams.

“This is what we plan and drill for all year, and we’re ready to get out there,” Mr. McHugh said.

New York’s electrical grid is especially sensitive to heat because most of its cables and transformers are stored underground, instead of on poles in the open air. While underground cables are less vulnerable to wind, snow and falling trees, they are harder to cool when the streets and sidewalks above them get hot.

To help prevent blackouts, Mr. McHugh urged New Yorkers to conserve power by running dishwashers and laundry machines at night or early in the morning, when it’s cooler out.

“Also raise the temperature a little bit on the air-conditioner,” he said. “Every little bit helps. If everybody’s doing it, you’re multiplying it by millions.”

Are heat waves in New York City becoming more common?

The only heat wave to hit New York City last year happened in September, said David Stark, a meteorologist with the National Weather Service of New York.

But Elijah Hutchinson, executive director of the Mayor’s Office of Climate and Environmental Justice, said he fully expected New York to experience more frequent, intense heat waves and hotter days in the coming years.

Department data suggests that by the 2030s, the city could see an extra 35 days of temperatures above 82 degrees each year, Mr. Hutchinson said.

“Heat is one of the biggest climate-related killers in New York City,” he said.