The upcoming Chicago Marathon is expected to be held in warmer-than-average weather conditions this coming 11th.
The National Weather Service (NWS) forecasted a peak temperature of around 73 degrees Fahrenheit on the day of the race. While the 7:30 AM start time will feel relatively comfortable in the 60s, temperatures are expected to gradually rise to around 70 degrees by 10:00 AM and reach the mid-70s by afternoon.
The historical average high temperature in Chicago on October 11 is approximately 65 degrees. Consequently, this year’s race may take place under hotter-than-usual conditions.
Race organizers deemed the weather conditions “not ideal,” issuing a yellow flag advisory and urging participants to “slow down their usual pace and stay adequately hydrated.” General participants running the course for extended periods may be particularly susceptible to the heat as it coincides with the peak temperature hours.
Humidity is also considered a significant variable. Certain sections of the Chicago downtown course receive relatively less cooling effect from Lake Michigan and feature extensive asphalt and concrete, making temperatures 3 to 5 degrees higher than other areas. High dew points can further hinder sweat evaporation, making it difficult to lower body temperature and increasing physical strain from the heat.
Meanwhile, road closures and traffic controls will be implemented throughout downtown from 4:00 AM to 6:00 PM on the day of the event. Closure and control times vary by section. Drivers are advised to check controlled sections and detour routes in advance and avoid traveling through downtown by vehicle if possible.
This year’s Chicago Marathon is set to draw over 55,000 participants from more than 100 countries and all 50 U.S. states.
