How Much is Climate Change Slowing Down Runners

Posted on 09 October, 2023 by Paul Ronto

We’ve analysed 19.6 million marathon results from over 30,000 marathons. In our new study, we concluded that the world is getting slower. In this article, we look at how the slow down is affected by increasing temperatures and the weather in general.

global warming effects on runners

What our analysis shows is that:

  1. The average runner adds 1 minute 25 seconds to his/her marathon finish time for every additional degree F
  2. The average runner adds 6 seconds a year due to the general temperature trend.

marathon finish time trend temperature

Global temperature increase

We used the data from The National Oceanic and Atmospheric Administration to estimate the rate at which the average annual temperature is changing. We established that the average yearly temperature is changing by 0.07 degrees Fahrenheit. This might seem like a negligible change, but it has its effects.  

temperature trend

Temperature and results

We saw that there is a clear trend that, finish times get slower with the increase in temperature. It turns out that the temperature during a race is responsible for over 30% of the variance in finish times. This means that climate is a huge factor in runners finish times. 

But the slow-down is not due only to global warming - the distribution of races at different temperatures has changed. With more events popping up around the world, we see more and more races held at high temperatures.

distribution of races

From the chart above we see that there are more and more races held at temperatures above 60 degrees, which has an impact over the finish times.

As we can see there is a clear differentiation in the average finish times based on the temperature when the race was held.

marathon finish times based on temperature

What is also noteworthy here is that the weather is not the only factor, we see that participants are getting slower in each temperature range and that they are getting slower at a higher rate in the warmer races.

Special cases

We also decided to dig deeper into some of the biggest races worldwide and to see, how the weather is affecting the runners.

Chicago Marathon

The temperature in Chicago is on the rise - the average temperature at the event has risen by 5 degrees F in the last 18 years. It also has a big variability - between 35 and 80 degrees. 

chicago temperature

But the trend between finish time and weather is still clear. 

chicago finish time

And for Chicago temperature is a great predictor for the marathon finish times, with a very small margin of error.

chicago temperature prediction

London Marathon

In London, the temperatures on race day vary between 40 and 60 degrees F. 

london temperature

And the relationship between temperature and finish time is strong. Even if the temperatures are not too volatile, they exert a significant effect.

london marathon finish time

And the predictions we can make about the finish times based on the weather have a small margin of error.

london temperature prediction

Boston Marathon

The temperatures at Boston marathon are quite volatile. They range between 40 and 75 degrees F. 

boston temperature

As we know the selection process for the Boston marathon is gruelling. But still even the best runners are still human, and the weather affects them strongly. 

boston marathon finish time

And here we can see, that the more prepared the runners, the more weather is the thing that is the outside force shaping their performance. Here we see that the predictions based on temperature are quite accurate. 

boston marathon prediction

New York Marathon

new york temperatue

In New York, the temperature is slowly rising, but it's also important to note that there is a huge variation in the temperature on the date of the event. The temperatures range from 40 to 70 degrees. And there is a strong relationship between finish time and weather.

new york finish time

Berlin Marathon

In Berlin, the temperature is actually declining. And it is contained in the interval between 50 and 70 degrees F. 

berlin temperature

Even, though the temperature here fluctuates in a smaller range, it still has a strong impact on the performance of the runners, as it was for Londoners. 

berlin marathon finish times

And we see here as well that the temperature on race day has s huge impact on the performance of the runners. 

Marine Corps Marathon

The temperatures on race day vary between 45 and 70 degrees F. 

dc temperature

And here again, we see that the trend is clear - the warmer the race day, the slower the average runner. 

martine corps finish time

LA Marathon

The temperatures for the LA Marathon vary between 50 and 80 degrees. And it is also one of the hotter races. 

LA temperature

Here we see that the participants are slower than the average runner. And that still the hotter it is, the slower the runners are. 

la finish times

Vienna Marathon

The temperatures in Vienna move is a narrow range - between 48 and 68 degrees. With most races at around 55 degrees. 

vienna temperature

This helps Vienna runners to show more consistent results. But still, we see that the outside temperature plays a role. 

vienna finish time

Amsterdam Marathon

Amsterdam marathon is one of the cooler races - with temperature ranging between 40 and 60 degrees. 

amsterdam temperature

And here as well we see that the best results are obtained at around 42-43 degrees F, which is the optimal running temperature. 

amsterdam finish time

About the researchers

The study is a product of collaboration between Paul Ronto and Vania Andreeva Nikolova. Ronto is an avid runner with 6 marathons under his belt and RunRepeat's Content Director. Nikolova holds a Ph.D. in Mathematical Analysis.

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Paul Ronto
Paul Ronto
Over the past 20 years, Paul has climbed, hiked, and run all over the world. He has summited peaks throughout the Americas, trekked through Africa, and tested his endurance in 24-hour trail races as well as 6 marathons. On average, he runs 30-50 miles a week in the foothills of Northern Colorado. His research is regularly cited in The New York Times, Washington Post, National Geographic, etc. On top of this, Paul is leading the running shoe lab where he cuts shoes apart and analyses every detail of the shoes that you might buy.