When Street Temps are Hot, Subway Platforms are Even Hotter

The world is currently enduring its 13th consecutive record-breaking month of heat, surpassing pre-industrial levels by 1.5 degrees. Amidst this scorching heat, New York City streets are sweltering, with the first heatwave coming as early as June this year and striking again in late August. But for subway passengers, the stations underground have long reached unbearable temperatures, troubling both straphangers and transit officials alike. An Instagram group named “SubwayCreatures” recently posed a question: “Which subway station is the hottest?” The post garnered thousands of responses. So we went to four of the most frequently mentioned stations, armed with a thermometer, to find out.

Subway platform heat has become an increasingly pressing issue in New York, particularly in recent years during the summer months. New York’s average annual temperature has warmed by 3°F since 1970, increasing at a rate of 0.6°F per decade. Projections suggest another potential 3°F rise by 2080, with the most significant warming expected in northern regions of the state, says the NYS Department of Environmental Conservation.

People experience heightened discomfort both above and below street level in Manhattan. Currently, only 8 stations in New York are equipped with cooling systems, and an additional five have fans installed. Last year, in response to growing concerns, the MTA issued a Request for Information seeking cooling technologies for subway platforms across New York City. However, visible improvements in station cooling have yet to be realized.

‘The team is evaluating what could be applicable in the subway system and will use the information collected when ready for the next step in the process, either pilot programs or additional requests for information,” stated Fabrizio Raho, Contracts Supervisor of MTA. “I don’t have anything else to share at the moment.”

With revenue from congestion pricing off the table after Gov. Kathy Hochul postponed “indefinitely” the implementation that was initially expected to start in June, it means for the moment MTA’s balance sheet does not show any prospect for investing in cooler subway stations.

A recent report by State Comptroller Thomas P. DiNapoli highlighted that while New York State stabilized MTA’s finances last year, the transit agency’s capital program faces significant delays due to funding challenges. These delays not only hinder essential maintenance and upgrades crucial for attracting riders and increasing fare revenue but also jeopardize the MTA’s next capital plan. DiNapoli stressed that relying on borrowing to cover capital fund shortfalls could strain the MTA’s operating budget, reducing resources available for daily operations and goals such as improving service.

My objective was to gather firsthand data from subway riders to provide an accurate depiction of the conditions. I collected my data on June 21st. On that day, the maximum temperature reached 100° Fwith the atmospheric temperature already at 79°F early in the morning. At street level, my thermometer registered 88° at the 1st Avenue-14th Street station on the L train. Moving to the mezzanine level, the temperature was slightly cooler at 86°F. Descending to the platform, I encountered a surge of hot air from the train engines, reaching 90° when trains were absent and soaring to 95°F when they arrived. I realized that my laser thermometer was registering surface heat rather than atmospheric temperature. Despite not being designed for atmospheric measurements, it reflected significantly elevated heat that was reflected from various objects. I could sense this warmth on my skin, and the data fluctuated noticeably. To simplify, I compare the thermometer readings from street level to underground, analogous to how scientists assess temperature variations when a thermometer malfunctions.

Boarding the L train, the journey took me to Union Square at 14th St. The platform there features high ceilings and numerous large ceiling fans that maintain circulation, keeping the temperature hot but bearable at 94°F as there was enough air circulation. Moving to the mezzanine level and descending to the 4, 5, and 6 train platforms heading towards downtown and Brooklyn revealed intense heat. The thermometer registered 98°F at the mezzanine level and rose to 99.5°F degrees on the platforms by 8:45 am, causing noticeable sweating despite purchasing an iced latte upon entering the subway, [The ice quickly melted.] The street to platform level temperature difference was more than 10°F.

At the 4th Street station for the 4, 5, and 6 trains, temperatures soared to between 115°F and 125°F. A train was just leaving, and the heat was it generated stayed on the platform. Fahmida Hossain, a medical ethicist working in New York, voiced her frustration amid the stifling conditions, ‘I should have started early and taken the bus, [rather] than melted in this heat.’ Other straphangers, drenched in sweat, clutched personal fans around their necks or in their hands, impatiently waiting for the train and complaining about the heat. The platform level temperature was 23°F to 33°F higher than the street level.

Taking the L train once more to 14th St. and 8th Ave., I found this station to be exceptionally hot, registering temperatures as high as 115°F . It felt oppressive, making breathing difficult. Cleaning staff informed me that near the elevator, temperatures reached a staggering level. My thermometer recorded 165.9°F there, describing why they actively avoid this spot. I also spoke with a conductor who said this station is the most challenging due to the prolonged stops of two L trains, trapping heat with low ceilings and minimal ventilation.”

This station feels like I’m in a pot of boiling water on the fire!” exclaimed Windy Smith, a straphanger. “I hope I don’t have to wait for the train on the platform. I usually just hop on the train, even if cleaning crews are working. It’s a bit more bearable inside.”

While subway dwell times are typically short, prolonged exposure to such extreme temperatures can be hazardous. Each summer, over 350 New Yorkers die prematurely due to hot weather, constituting approximately 2 percent of all deaths from May to Sept. This includes an average of seven deaths directly attributed to heat stress and around 345 deaths where heat exacerbates underlying illnesses. The rise in heat-related deaths correlates with increasingly hotter summers featuring more days above 82°F, just below extreme heat levels, according to city data. The issue of global warming exacerbates New York City’s heat waves. Climate projections for the city indicate that while an average of 2 heat waves occurred annually between 1970 and 2000, this number could increase to seven annually by 2050 under the high estimate scenarios. Similarly, the average number of days exceeding 90°F, currently at 18 annually, is projected to triple to 57 days by 2050.A recent report from Nature, a weekly journal of science, highlighted the escalating underground heat in subway stations as a looming “silent hazard.” Rising subsurface temperatures threaten to disrupt transit systems by overheating subway rails, necessitating train slowdowns or stops to prevent incidents. The economic impact of delayed public transportation services and potential health risks for commuters are significant concerns associated with this emerging problem.

”Summers seem longer and hotter these days,” says Aaron Liman, a regular subway commuter and a lifelong resident of New York, “Even five years earlier, subways cooled down after August, but now it feels very hot during the fall.” New York has a temperate climate but in years past, its cold winters stretched for a much longer period than its short, hot summers. Unfortunately, that meant that the designers of the the city’s subway system, which began construction in 1904, built it with a focus on conserving heat within underground stations. But New York like many other northern cities, is now feeling the impact of global warming. As the frequency of hot days and temperatures increases, there is a growing challenge to effectively release accumulated heat from infrastructure during the summer months.