Marathon Organizers Will Shift Race Dates to Beat Heat
As extreme temperatures rise, more races will adjust calendars and start times to protect participants from heat-related risks.
Updated on Oct. 2, 2026 in Running
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Race organizers across the United States are increasingly rescheduling marathon dates and shifting start times to earlier hours to mitigate the health dangers of rising temperatures. These changes respond to a trend of warmer weather that has recently led to race cancellations and necessitated new safety measures for runners.
Why it matters
Rising temperatures create a significant physiological strain, as the body struggles to dissipate heat during intense physical exertion. These adjustments aim to reduce the risk of heat-related illness by avoiding peak temperatures during long-distance endurance events.
A Climate Central analysis of 221 races projected that 46 of 51 major U.S. marathons will lose optimal physiological conditions by 2045 due to warming. This follows records showing 2024 was the hottest year on record and the contiguous U.S. experienced its warmest July in 2026.
The players
Climate Central
An independent research organization that analyzes and reports on the impacts of climate change.
World Meteorological Organization
An international agency that tracks global weather patterns and climate projections.
The details
Running a 26.2-mile marathon requires the body to dissipate significant heat, as only about 25% of energy expended goes toward forward movement while the rest generates internal heat. When environmental temperatures exceed 60 degrees F, the cardiovascular system must work harder to shuttle blood to the skin for cooling, which can lead to physiological distress. By moving events to cooler months or earlier in the morning, organizers aim to keep environmental conditions within a range where the body can more effectively manage thermal regulation.
Timeline
2023: Twin Cities Marathon was canceled due to heat and humidity.
2024: The Earth recorded its hottest year on record.
March 2026: Los Angeles marathoners were offered a shortened 18-mile route option.
2027: The Twin Cities Marathon will officially move its race date to later in October.
Health Landscape
Endurance sports are increasingly adapting to a warming climate by realigning event schedules with historical temperature data. This trend reflects a broader necessity to safeguard participants as global temperatures are forecast to rise by more than 1.5 degrees C between 2025 and 2030.
Runners should monitor local race guidance regarding heat protocols and be prepared to adjust personal exertion goals during high-temperature events. If you have concerns about your tolerance for exercise in heat, it is worth discussing your individual cardiovascular risk with your doctor.
The takeaway
When training for endurance events in warming conditions, recognize that heat tolerance is a critical factor for safety. It is advisable to track local weather patterns and consider shorter race alternatives or earlier start times when temperatures consistently exceed 60 degrees F.
Further reading
For more on managing athletic performance in changing weather, explore our Running archives.
Source note: This article includes information reported by MinnPost.
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Should local event organizers reschedule outdoor races to prioritize runner safety during extreme heat?
