New York City entered an early-season heat event this week as Mayor Zohran Kwame Mamdani and New York City Emergency Management (NYCEM) activated the city’s Heat Emergency Plan on Monday, May 18, 2026, ahead of two days of dangerous heat and degraded air quality across all five boroughs. The activation came as the National Weather Service issued a Heat Advisory effective from 11 a.m. Tuesday, May 19, through 8 p.m. Wednesday, May 20, with heat index values forecast between 91 and 96 degrees during peak afternoon hours.
City officials warned that the timing of the heat — arriving roughly 30 degrees above seasonal averages — could catch New Yorkers off guard before the typical summer adjustment period. Cooling centers opened across every borough, and outreach teams expanded operations to reach residents most at risk of heat-related illness.
What the Heat Emergency Plan Covers
The Heat Emergency Plan coordinates action across multiple city agencies whenever extreme heat threatens public health. According to the NYC Mayor’s Office press release issued on May 18, key components of the plan include opening cooling centers in every borough, expanding outreach to older adults, people with chronic health conditions, and unsheltered New Yorkers, issuing targeted alerts through the city’s Advanced Warning System, monitoring health impacts in real time, and strengthening coordination with utilities, hospitals, and community organizations.
“Just as New Yorkers look out for one another through the coldest days of winter, we must do the same through the hottest days of the year,” Mayor Mamdani said in the May 18 statement. He urged residents to plan ahead, stay hydrated, and check on neighbors during the advisory window.
NYCEM Commissioner Christina Farrell noted that the early-season timing carried added risk. “Tomorrow, we’ll be seeing temperatures that feel more like the middle of summer than the middle of May,” Farrell said. “Because it’s arriving early in the season, New Yorkers may not be thinking about heat safety yet.”
Heat Index Forecasts Across the Boroughs
NWS data cited by the city projected heat index values ranging from 91 to 96 degrees on Tuesday afternoon, with the highest readings expected between approximately 1 p.m. and 5 p.m. in parts of the Bronx, northern Manhattan, and Staten Island. The advisory remained active through Wednesday evening as humidity kept apparent temperatures elevated.
A heat advisory is issued by the NWS when the combination of heat and humidity is expected to make it feel like 95 to 99 degrees for two or more consecutive days, or 100 to 104 degrees for any length of time, according to the Weather Service’s published criteria.
Air Quality Alerts Compound the Risk
Layered on top of the heat was a separate Air Quality Health Advisory issued by the New York State Department of Environmental Conservation, which the New York State Department of Health flagged in its May 18 press release. The advisory cited ozone levels reaching an Air Quality Index of 105, considered “unhealthy for sensitive groups.”
State Health Commissioner Dr. James McDonald reminded residents to factor air quality into outdoor planning. “Remember to stay cool, drink water and don’t overexert yourself during extreme heat which can be life threatening for those with chronic conditions such as asthma,” McDonald said in the state release.
People with cardiovascular disease, respiratory conditions such as asthma, young children, older adults, pregnant individuals, and those who exercise or work outdoors were advised to limit strenuous outdoor activity, particularly during the afternoon and early evening when ozone concentrations peak.
Why Ozone Spikes Matter in Hot Weather
Ground-level ozone forms when emissions react with sunlight and heat, which is why air quality often worsens during heat events. The state Department of Environmental Conservation publishes daily air quality forecasts, and residents can check current conditions at airnow.gov before heading outdoors.
Cooling Centers, Outreach, and Resources for New Yorkers
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To help residents find relief, cooling centers opened across all five boroughs on May 19 and 20. Locations include senior centers, libraries, community centers, and NYCHA developments, with hours and accessibility details that vary by site. The city encouraged residents to confirm hours by phone before traveling to a location.
New Yorkers can find a nearby cooling center, including accessible and pet-friendly sites, by visiting the city’s Cool Options Finder at finder.nyc.gov/coolingcenters or by calling 311. Service animals are permitted at every cooling center.
Beyond indoor sites, the city’s Cool It! NYC program offers outdoor cooling resources such as spray showers and public drinking fountains in parks across the five boroughs.
Outreach to Vulnerable Residents
Department of Homeless Services outreach teams expanded around-the-clock operations during the advisory, engaging unsheltered New Yorkers and encouraging them to access shelter or cooler indoor settings. Outreach workers distributed water and other essentials. Anyone who sees a homeless New Yorker who may need assistance can contact 311 by phone or through the city’s mobile app to request outreach.
The state also highlighted the Home Energy Assistance Program (HEAP) Cooling Assistance Benefit, which helps eligible households purchase and install an air conditioner or fan. Office of Temporary and Disability Assistance Commissioner Barbara C. Guinn said HEAP cooling assistance “can be a lifeline for households without an air conditioner that have no other way to ward off the dangerous heat.”
Health Guidance for Residents During the Advisory
NYC Health Commissioner Dr. Alister Martin stressed that air conditioning remains the most reliable defense against heat-related illness. “The best way to prevent heat-related illness is to remain in a cool, air-conditioned environment — a fan alone isn’t enough,” Martin said in the city’s May 18 statement.
Martin advised those spending time outdoors to stay in the shade, drink water consistently, and take frequent breaks. He also urged residents to watch for signs of heat stroke, including difficulty breathing or a rapid heartbeat, both of which warrant a call to 911.
City officials reiterated that most heat-related deaths in New York City occur after prolonged exposure to heat indoors without air conditioning, underscoring the importance of checking on neighbors and family members who may be at higher risk.
The state Department of Health lists heat stroke, heat exhaustion, heat cramps, and heat rash among the most common heat-related conditions. Warning signs can include heavy sweating, weakness, nausea, headache, confusion, and a rapid pulse. The department’s Heat Risk and Illness Dashboard provides forecasted heat-health risk levels by area.
Staying Informed Through the Heat Wave
New Yorkers can sign up for free emergency alerts through Notify NYC by texting NotifyNYC to 692-692, calling 311, downloading the Notify NYC mobile app, or following @NotifyNYC on social platforms. Statewide alerts are available by texting a county or borough name to 333-111.
For ongoing tips, the city maintains a public-facing extreme heat guide at nyc.gov/beattheheat, and the state offers heat-safety guidance at health.ny.gov/extremeheat.
With the advisory set to lift at 8 p.m. on Wednesday, May 20, temperatures were forecast to drop into a more typical late-spring range heading into the weekend. City and state officials, however, used the early-season event as a reminder that heat preparedness should begin well before the official start of summer — particularly for residents without reliable access to air conditioning or air quality information.
