Taking to social media to complain about hot subway rides? You're not alone: study

A new study in the journal Nature Cities shows that as temperatures rise aboveground, the number of subway riders reporting uncomfortable heat belowground increases

Commuters, residents and tourists who take to social media during warm months to complain about sweltering subway systems in New York, Boston and London should feel vindicated — new research says they aren't alone.

As temperatures rise aboveground, the number of subway riders reporting uncomfortable heat belowground increases, according to a new study in the journal Nature Cities on Tuesday. This could worsen as climate change, driven by the burning of fossil fuels, makes for a hotter planet.

Northwestern University researchers analyzed more than 85,000 crowdsourced social posts on the social platform X and Google Maps reviews from 2008 to 2024 in those three major cities’ subway systems. They searched for keywords related to being too hot — or what they called “thermal discomfort” — in those metropolises, which are some of the world’s oldest and busiest. The experts looked for terms such as “hot” and “warm” while filtering out results that did not seem to relate to temperature, such as “hot dog.”

The study’s authors said subway riders may expect temperatures to be naturally cooler underground. They found that a 1-degree Fahrenheit (0.56-degree Celsius) increase in outdoor temperature led to a 10% increase in complaints in Boston, 12% in New York and 27% in London. Earth’s average temperature warmed 1 degree F (0.56 degrees C) from 2008 to 2024, according to the National Oceanic and Atmospheric Administration.

The researchers analyzed posts across seasons, time of day and day of week.