What Makes Paris 2024 a Race to Records? PART 3: The Influence of Temperature

Held in late September and early October, these races benefit from favorable autumn mornings, with average temperatures around 10°C and humidity around 70%—ideal conditions for peak performance. Although wind is usually strong in Chicago, Kelvin Kiptum was notably fortunate on his record-breaking day, as the wind was nearly absent and favorable. That morning, we sensed something extraordinary was about to happen.

History of Climate at the Olympic Marathons

When focusing on the temperature of recent Olympic marathons, it reveals a clear correlation between high performance and cooler average temperatures.

Figure : Correlation between Olympic winning times and air temperature.

Usually held in August, the Olympic marathons often present athletes with challenging conditions that undoubtedly impact performance. Although the event is always held in the summer, climatic conditions vary considerably from one venue to another. As the Olympic Games are held around the world, it is challenging to make direct comparisons between marathon performances at different events. However, an analysis of past races reveals some interesting trends.

Notably, there is a clear correlation between finishing times and temperature rather than location alone. Across Olympic marathons, humidity typically hovers around 65-70% (with the women’s race in Rio 2016 reaching a peak of 80%). Performance levels generally improve in cooler conditions, whether the event is held in South America, Europe, or Australia.

An outlier in this trend is the 2008 Beijing men’s marathon, where Samuel Wanjiru and Jaouad Gharib crossed the finish line in just over 2h10m, about three minutes ahead of bronze medalist Tsegay Kebede, shattering the previous Olympic record of 2h09m21s set in 1984. Under a scorching sun, this remarkable performance is often attributed to Wanjiru’s youthful energy, as he was only 21 years old at the time.

Climatic Conditions during the Paris 2024 Marathons

On August 10th in Paris, the men’s race began with temperature and humidity at 17.3°C/73%, rising to 21.9°C/61% as the race progressed. The following day, the women’s race faced even hotter and drier conditions, starting at 19.8°C/65% and reaching 25.7°C and 50% by 10:00 am.

While regional climate estimates provide a general idea, a full understanding of the stress athletes face during the race requires a closer focus on local climate measurements throughout the course.



Figures: Average humidity, temperature, and wind speed measured at the finish line by World Athletics’ hyperlocal monitoring station.

To obtain precise climate data along the marathon route, World Athletics conducted hyperlocal monitoring of humidity, temperature, and wind between 8:00 and 11:00. Compared to the broader temperature and humidity data from Météo France for the entire Paris region, local measurements showed temperatures about 1°C higher and humidity 5% lower at 8:00 for both races. By 10:00, the differences grew to nearly 2°C higher and 10% lower humidity. This trend of rising temperatures and decreasing humidity continued as the races progressed, with a 2°C and 7% difference between August 10^th and 11^th, indicating a drier environment during the women’s race.
Wind measurements showed no significant differences between the two days and were considered negligible, with speeds below 5 km/h, having minimal impact on the runners' pace.
Notably, temperatures were much lower than expected in mid-August. A large proportion of runners had completed heat training sessions, which, despite the cooler race-day conditions, still significantly impacted their performance.

The Influence on Performance

A key metric for evaluating performance under varying climate conditions is the Wet Bulb Globe Temperature (WBGT), which combines air temperature, humidity, wind speed, and solar exposure to quantify heat stress from sunlight, directly impacting athletes.
In the Paris 2024 marathon, the WBGT was 1°C higher in the women’s race than in the men’s, likely adding an extra level of physiological strain on the athletes.

Figure : Wet Bulb Globe Temperature (WBGT) readings were obtained through hyperlocal measurements conducted by World Athletics.

In hot conditions, the body needs to thermoregulate more efficiently. Heart rate and metabolic rate increase, leading to anaerobic energy contribution at marathon pace. In long-distance events like the marathon, the primary method of thermoregulation is evaporative heat loss, which can intensify dehydration as sweating increases. Essentially, the challenge for the body is managing heat stress while maintaining adequate cardiac output for performance.
Given this, and noting that the women’s race was, on average, 7 minutes slower than their qualifying times, it’s evident that climate conditions likely affected their performance. In comparison, the men’s race was 4 minutes slower than personal or season bests, benefiting from lower temperatures and reduced stress. This aligns with the earlier observation that the best Olympic performances typically occur under cooler conditions.
To further examine temperature's impact on performance, this calculator, based on the Flouris formula, provides valuable insights. Although designed for amateur runners, it effectively demonstrates how temperature affects performance.

	OG Marathon	Best Perf 2023	PB	Calculator
TOLA	2.06.26	2.04.58	2.03.39	2.06.17	for 21°C based on 2023 perf
ABDI	2.06.47	2.03.47	2.03.36	2.05.6
KIPRUTO	2.07.00	2.04.02	2.02.16	2.05.21

Figure : Example of performance decrements calculated using the Enduraw calculator based on the Flouris formula.

Ultimately, What Builds a Record?

The Paris 2024 Olympic marathons emerged as the must-run event of the summer. With a challenging course profile, athletes had to adapt their training to tackle obstacles rarely seen in marathon racing. At first glance, the Paris course appeared among the toughest in Olympic history, yet it proved more conducive to negative splits than previous editions.

This shift can be attributed to athletes’ strategic planning, the absence of a clear front-runner, and, most significantly, advancements in international performance standards driven by innovations in materials and training sciences. Over the past year, performance science has advanced, elevating marathon running to new levels.

These improvements, combined with more favorable-than-expected climate conditions, enabled the world’s top marathoners to excel on the streets of Paris. The spectacular course kept athletes motivated and focused. Although many anticipated that the climbs would negatively impact race times, the opposite occurred, as various factors played to the athletes' advantage.

Initially seen as a major challenge for both professionals and amateurs, the Paris 2024 Olympic Marathon provided an exhilarating course that encouraged high-level performances. Though not a flat, fast route, it fostered intense race dynamics. With enthusiastic crowds and outstanding athlete performances, this marathon will be remembered as a historic event, breaking two Olympic records. It was also the first time that amateurs and elite athletes shared the same course and experienced the unique thrill of running a marathon together.

Anthony Saliou and Joseph Mestrallet for Enduraw.