86% of marathons projected to experience decline in odds of ideal running temperatures by 2045
\n KARACHI
\nA new scientific analysis has warned that climate change is rapidly shrinking the window of \u201ccool days\u201d that allow marathon runners to achieve their best performances, posing an increasing challenge for athletes and organisers of the world\u2019s premier long-distance races.
\nThe report, titled \u201cRunning out of cool days: How climate change is decreasing the odds of optimal marathon conditions\u201d, was released by Climate Central ahead of the New York City Marathon.
\nIt examines how rising global temperatures are affecting marathon performance conditions across 221 global races, including all seven Abbott World Marathon Majors.
\nAccording to the study, 86% of marathons analysed (190 out of 221) are projected to experience a decline in the odds of ideal running temperatures by 2045. This includes all major races in Tokyo, Boston, Berlin, Chicago, London, New York, and Sydney.
\nAmong the elite male runners, Tokyo currently offers the best odds of ideal race-day conditions, with a 69% chance of hitting the performance \u201csweet spot\u201d. But that advantage won\u2019t last: the probability is expected to fall by 12 percentage points to 57% by 2045 if emissions continue at current rates.
\nElite women, who perform better in warmer temperatures than men, are somewhat more resilient to climate shifts. They currently have a 78% chance of optimal race-day temperatures at Tokyo, rising slightly to 85% by 2045. Still, researchers emphasise that even small changes in average conditions can have significant impacts on elite performance and race safety.
\nThe analysis also found that London offers the most favourable conditions for elite women at present, with an 87% likelihood of optimal temperatures, while Berlin presents one of the least favourable outlooks. By 2045, the odds of ideal conditions for elite female runners in Berlin are expected to drop from 40% to 29%.
\nThe report found that the exceptional heat at the 2025 Tokyo and Berlin Marathons pushed conditions far beyond the optimal range for both recreational and elite runners and that human-caused climate change made those temperatures significantly more likely.
\nOn March 2, 2025, the day of the Tokyo Marathon, the average temperature was 15.2\u00b0C (59.4\u00b0F), about 8.2\u00b0C warmer than normal, reaching a Climate Shift Index (CSI) level of 3, meaning the unusually warm conditions were three times more likely due to climate change.
\nSimilarly, Berlin\u2019s race on September 21, 2025, saw an average temperature of 20.7\u00b0C, about 6.7\u00b0C warmer than normal, with a CSI level of 2, indicating the heat was twice as likely because of global warming.
\n\u201cHeat waves are already rewriting race history,\u201d said Climate Central in its release. \u201cFor many marathons, what used to be ideal race conditions are becoming the exception rather than the rule\u201d.
\nResearchers identified precise \u201csweet spots\u201d for marathon temperatures where runners perform their best. For elite men, that optimal average is 4\u00b0C; for elite women, it\u2019s 10\u00b0C. Recreational runners perform best at slightly higher temperatures, around 6\u00b0C for men and 7\u00b0C for women.
\nThe analysis draws from global temperature records, climate model projections, and Climate Central\u2019s proprietary Climate Shift Index to estimate how the probability of ideal temperatures will evolve over time, using future climate scenarios aligned with the SSP3-7.0 pathway.
\nWhile the findings show a clear long-term decline in favourable marathon conditions, the report also notes that some adaptations could help mitigate the impacts.
\nOne adaptation measure is to start races earlier in the morning, when daily low temperatures prevail. Researchers found that adjusting race times to sunrise could significantly increase the chances of ideal temperatures for elite men by 44 percentage points in London, 31 points in Tokyo, and 27 points in Boston by 2045.
\nHowever, this approach doesn\u2019t benefit all groups equally. Because elite women perform better at slightly higher temperatures, earlier starts could actually reduce their odds of optimal conditions, notably in Tokyo (down 41 points) and Boston (down 18 points).
\nThe Climate Central concludes that reducing fossil fuel pollution remains the only lasting solution to preserve the cool, comfortable race-day conditions that support peak performance and athlete safety.
\nAround 1.1 million people finish a marathon every year, but as the planet warms, the chances of running in optimal weather are rapidly diminishing even for races in traditionally cool climates.
\nVeteran marathoners and record holders are already seeing the changes firsthand.
\n\u201cClimate change has altered the marathon,\u201d said Catherine Ndereba, former marathon world record holder and two-time world champion. \u201cDehydration is a real risk, and simple miscalculations can end a race before it begins. Every step now carries a message that if we don\u2019t take care of our planet, even our strongest strides will fall short\u201d.
\nMhairi Maclennan, the fastest British finisher at the 2024 London Marathon, said ideal race conditions are \u201cslipping away\u201d.
\n\u201cAt the elite level, conditions make or break a performance,\u201d she said. \u201cWe train day in, day out for years, only for that elusive target to drift further away as ideal temperatures become rarer\u201d.
\nKenyan legend Ibrahim Kipkemboi Hussein, the first Kenyan to win both the New York City (1987) and Boston (1988) marathons, described how races have changed with the warming climate.
\n\u201cThe climate is part of the course now,\u201d Hussein said. \u201cDehydration and exhaustion come faster; a small mistake in pacing or hydration can cost everything. If we don\u2019t protect the planet, the records of the future and the joy of running itself are at risk\u201d.
\nFor Climate Central, the message is clear: marathoners and their races are on the front lines of a warming world.
\nWhile earlier starts and logistical adaptations may buy time, the only sustainable path to preserving record-breaking conditions is to curb global emissions and stabilise the planet\u2019s temperature rise.
\n\u201cThe cool, comfortable race-day conditions that make history are running out,\u201d the report warns. \u201cIf we fail to act, the world\u2019s great marathons and the runners who define them will be racing against more than the clock\u201d.<\/p>\n","protected":false},"excerpt":{"rendered":"
86% of marathons projected to experience decline in odds of ideal running temperatures by 2045 KARACHI A new scientific analysis has warned that climate change is rapidly shrinking the window of \u201ccool days\u201d that allow marathon runners to achieve their best performances, posing an increasing challenge for athletes and organisers of the world\u2019s premier long-distance […]<\/p>\n","protected":false},"author":2,"featured_media":511321,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[],"class_list":{"0":"post-511313","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-sports"},"yoast_head":"\n