The Tour de France has weathered its share of interruptions over the years, from rider strikes and roadblocks by climate activists to the regular farmers’ protests. There have been tangible climate issues too, from stages raced in 40ºC temperatures to the 2019 Tour, where stages 19 and 20 were shortened due to mudslides.
But new research shows the likelihood of extreme heat in France in July, when the race takes place, is increasing steadily.
Published in Scientific Reports, the study, led by the French National Research Institute for Sustainable Development, looked at 50 editions of the race stretching back to 1974.
Heat-stress risk increasing
The study examined temperature and wet bulb temperature records (which assess other factors including humidity and solar radiation) to assess the level of risk of heat stress over this time, finding it had increased steadily.
The largest number of extreme-heat events were found to have occurred in the last 10 years. But the research concluded that the Tour has, so far, avoided the conditions of maximum health risk, in some cases by only a few days.
According to the study’s lead author, Ivana Cvijanovic: “In our analysis, we observe that the city of Paris, for example, has crossed the high-risk threshold for heat on five occasions in July, four of them since 2014. Other cities have experienced many days of extreme heat in July, but thankfully not on the date of a Tour de France stage.”
Cvijanovic says the Tour has been lucky so far, but predicts it’s only a matter of time before the race runs into a day or more of extreme heat.
Southern-French hotspots
Hotspots – literally – often on the Tour’s route include Toulouse, Pau and Bordeaux in the south west, as well as Nîmes and Perpignan in the south east. The study found high mountain stages present a low to moderate heat stress risk, though, despite the valleys on their approach sometimes being very hot.
The researchers point out that mornings are less prone to extreme heat than afternoons and that start times and routes might in future need to be altered to reduce risks, not only to cyclists but to spectators and event staff.
The UCI has had a heat protocol in place since 2023, which has been invoked in other races. But the researchers point out there’s little research on the effect of heat stress on elite athletes and no universal standard applied across different sports.
It’s not only the Tour de France that is at risk of extreme heat. It’s even more of an issue for the Vuelta a España, where temperatures in southern and central Spain in August frequently reach 40ºC and riders have been hospitalised due to heat exhaustion.
The queen stage of this year’s men's Tour Down Under was shortened due to the 40ºC heat and fire risk in South Australia in January.
There have been calls, meanwhile, for the Vuelta to swap its place in the calendar with the Giro d’Italia, where snow and freezing rain in Italy in May are often more of a problem than heat.
