Visual Crossing Blog

Does weather affect the results of the London Marathon?

The London Marathon

It's late April and for runners that means it's time for the London Marathon. Can weather change the race? In this blog we investigate how London Marathon finishing times vary with the weather.

Were previous marathons affected by weather?

First, let's take a look at the previous results and if they were affected by weather. Here I have populated the weather conditions for each of the marathons for the past 18 years using the Visual Crossing Weather add-in for Microsoft Excel . In addition, I have included the winning time for the men's and women's race and the overal average finishing time from the data found at marathonguide.com.
Temperatures and Past results of the London Marathon from marathonguide.com
Temperatures and Past results of the London Marathon (credit: marathonguide.com)

From the data, race day temperatures vary from a low of to a high of 9C to 23C. This is quite a range of temperatures! How does that affect the race times?

The average race time ranges from 4 hours 20 minutes to 4 hours 50 minutes. Could that be dependent on weather? Here's a graph of average race time against temperature. There is a strong correlation between the temperature on race day and the average finishing time. As temperature increases, so does the average race time.

Average London Marathon Finish Time by Temperature
Average London Marathon Finish Time by Temperature (degC)

Now let's look at how winner's times are affected by weather by comparing the temperature with the men and women's fastest finishing times. By simply viewing the data in the grid, we can see that there is a significantly smaller range of values for the winning times. Let's plot these on a graph against temperature to see how these values correlate.

London Marathon Winning Times by Temperature
London Marathon Winning Times by Temperature (degC)

For winners, the correlation is completely absent. Elite runners are not affected by the temperature experienced during the London Marathon - even for 2018, the hottest London Marathon ever.

How will 2019 year's weather affect the results?

This year, the forecast calls for a high temperature of 14.3C. That's close to the mean temperature of 14.8C. Runners may have been hoping for something a little cooler but I suspect spectators will be happy. Given our quick bit of investigation, the winning times may not be affected by the forecast, but the average finishing time certainly will be. Good luck to all those taking part!

Weather Forecast for the London Marathon 2019
Weather Forecast for the London Marathon 2019