Paul Grinvalds has participated in 114 marathons across all 50 states. Despite his experience, he struggles in temperatures exceeding 60 degrees Fahrenheit (15.5 Celsius). Like many runners, the challenge is due to the body’s inability to cool effectively during exertion.
Grinvalds, 68, from West Des Moines, Iowa, noted, “One thing about marathoners is typically we’re kind of stubborn. If we have a goal and it’s hot, a lot of times we’re still going to try to do that goal, which is just stupid because you’re almost guaranteed to have a very painful experience.”
The danger also extends to safety concerns. Marathon organizers now address climate change-induced heat by adjusting race dates and start times, and even offering participants shorter run options.
Starting in 2027, the Twin Cities Marathon in Minneapolis-St. Paul shifts from the first Sunday in October to later in the month. The change follows a 2023 cancellation due to record heat and a 2025 start temperature near 70 F (21 C).
Similar adjustments are seen in Sioux Falls, South Dakota, where the annual race moved from August to September. Other races like the Air Force Marathon in Dayton, Ohio, and Little Rock Marathon in Arkansas now start earlier to avoid peak temperatures.
Earlier in Los Angeles, March conditions prompted organizers to offer a shorter 18-mile option, sparking some criticism online. Only a small percentage chose the shorter route, and minimal hospitalizations occurred, which allowed completion of the event with safety as a priority.
Meg Treat, a marathon spokesperson, said, “We welcome feedback and it’s certainly something that caused a lot of discussion, but when we’re grading ourselves on it, it has to do with how safe our runners were on the day of the event and we’re very happy with the outcome.”
At the Twin Cities Marathon, race director Ed Whetham described cancelling the 2023 event as “devastating”. An analysis led to delaying the race for better conditions, accepting the risk of late October snow in favor of cooler temperatures for runners.
Temperature trends are concerning. The contiguous U.S. had its warmest July ever, and Earth’s hottest recorded year was 2024. Predictions by the World Meteorological Organization suggest a rise beyond 1.5 degrees C (2.7 degrees F) between 2025 and 2030 compared to the 1800s.
According to a study by Climate Central analyzing 221 races, conditions in the low 40s (6 or 7 degrees C) are ideal. By 2045, 46 of the 51 U.S. marathons reviewed might not meet these conditions. This highlights how climate change restricts outdoor exercise opportunities, as noted by Andy Pershing from Climate Central.
Jessica Murfree of the University of North Carolina-Chapel Hill researches climate change impacts on sports. She advises reconsidering event schedules across various sports and increasingly hot outdoor environments.
Moreover, extreme weather influences daily activities. Concerns about warm days indoors might shift preferences to activities like swimming.
Running marathons in the heat is notably difficult. The challenge lies in maintaining a balance between exerting effort and managing body temperature over an extended period.
Chris Minson, a University of Oregon professor, identified 50 degrees (10 C) as the ideal temperature for marathons. Warm temperatures require balancing blood supply to muscles for running and thermal regulation. Minson advises that athletes can acclimate to higher temperatures through consistent practice in warm conditions.
Some athletes, like John Seals, embrace heat as part of their training for ultramarathons. Training regimes include midday runs and sauna sessions to adapt. Still, exercise caution is key.
Douglas Casa, a kinesiology professor, supports the Twin Cities Marathon’s adjustment, considering the determination of many runners. He highlights the importance of adaptability in strategies to ensure safety.
The Associated Press’ climate and environmental reporting is supported by several private foundations. All content conforms to AP standards, available at AP.org.