A recent study published in *Nature Cities* highlights the growing issue of heat-related discomfort experienced by subway riders in major cities such as New York, Boston, and London. Researchers from Northwestern University analyzed over 85,000 social media posts and Google Maps reviews from 2008 to 2024, focusing on keywords related to thermal discomfort. The study revealed a clear correlation between rising outdoor temperatures and increased complaints about heat within subway systems. Specifically, a 1-degree Fahrenheit (0.56-degree Celsius) increase in outdoor temperature leads to a 10% increase in heat complaints in Boston, 12% in New York, and a substantial 27% increase in London.