Organizers of major marathons face growing challenges as warmer-than-expected temperatures increasingly complicate race-day conditions for both participants and event staff. Ted Metellus, chief event production officer and race director for New York Road Runners, which oversees the New York City Marathon, emphasized the unpredictable nature of weather during planning despite the known elements of course and distance.
The 2022 New York City Marathon highlighted these difficulties when unusually warm temperatures around 70 degrees in early November coincided with slower finishing times—on average 11 minutes longer than the previous year. This led organizers to expand heat mitigation efforts, including increasing the number of misting stations available to runners regardless of forecasted conditions.
Historically, the marathon has faced heat-related challenges before. The 1984 event, held during a late October heatwave with temperatures near 79 degrees and over 90 percent humidity, resulted in hundreds of runners receiving treatment for heat-related illnesses and the race’s first fatality. Jacques Busseraux, a 48-year-old French participant, collapsed mid-race and later died of cardiac arrest. Race founder Fred Lebow termed that event “the disaster of 1984.”
This year’s forecast calls for mostly cloudy skies and highs approaching 70 degrees at Central Park on race day, exceeding typical early November temperatures. Research shows that optimal running temperatures differ by runner category. Studies analyzing nearly 1.8 million marathon finishers across six major events found elite male runners perform best near 39 degrees Fahrenheit, while elite women fare better at around 50 degrees. Recreational runners tend to perform best between 43 and 44 degrees.
Experts attribute these differences to internal heat generation. Chris Tyler, an environmental physiology associate professor, explained that faster runners produce more body heat due to higher intensity but cope better with cooler weather. Conversely, slower runners generate less heat and can more easily tolerate warmer temperatures. Mike Tipton, a human physiology professor, described how the body attempts to cool itself by diverting blood flow to the skin, which reduces oxygen availability to muscles, leading to earlier fatigue and slower pace.
The dangers of extreme heat were underscored during the 2007 Chicago Marathon, which was halted mid-race after temperatures reached 87 degrees with high humidity and a heat index of 90. That day, over 300 participants required ambulance transport, 49 were hospitalized, and one runner died. Since then, Chicago Marathon organizers implemented a unified command center and a color-coded Event Alert System to coordinate responses and communicate heat risk, practices now adopted by other major races, including New York’s.
Some events have taken further steps to contend with rising temperatures. The Twin Cities Marathon in Minnesota will move from early October to later in the month starting in 2027 following a 2023 cancellation caused by a record-setting 92-degree day. Organizers noted that warmer overnight lows in recent years have diminished the traditionally cool, crisp fall conditions and expect the date change to lower race-day temperatures by approximately 10 degrees.
As climate change trends predict increasing temperatures during typical marathon seasons, the importance of heat acclimatization grows. Experts recommend 10 to 14 days of training in warm conditions to help the body adapt by increasing blood volume and sweat response, improving runners’ ability to manage heat stress.
An analysis projecting climate impacts on marathons worldwide concluded that by 2045, most races will face declining chances of ideal temperature conditions for peak performance among elite and recreational runners. The New York City Marathon is among the events expected to experience a decrease in optimal temperatures by two to five percentage points across various runner categories, underscoring the ongoing challenge of balancing athlete safety and performance amid evolving weather patterns.