Chicago Marathon Heat Varies by Location

Researchers studied heat during the Bank of America Chicago Marathon. They focused on Wet-Bulb Globe Temperature. This measure helps race staff protect runners from heat stress. The team wanted to know if heat stays the same across the whole course.

They placed sensors at five different points on the route. Data was collected in 2022, 2023, and 2024. Each sensor recorded readings every sixty seconds. The numbers were then averaged every five minutes. The scientists compared the stations using statistical tests.

Heat levels were not uniform. They changed by location and by time. Between 7:30 a.m. and 11:00 a.m., the average difference between stations was 2.6 degrees Celsius. At certain moments, the difference reached 9.3 degrees Celsius. These gaps appeared in all three marathon years. The results were statistically significant.

The pattern stayed the same even when looking only at times when runners were on the course. This means a single sensor cannot capture the full picture. Race organizers should use multiple stations. More data points lead to safer decisions for everyone running the race. Using several stations is the best way to understand heat along the route. One spot is not enough.