39 Olympic sites will host the competitions of the Paris 2024 Games in France, the majority of which will take place in Paris and its suburbs, notably athletics, swimming and cycling. Other regions, such as the Auvergne-Rhône-Alpes region, Aquitaine, Pays de la Loire, Bouches-du-Rhône and Tahiti, will host events such as surfing, sailing, golf and football. The variety of these sites represents a significant climatic diversity, and therefore a diversity of hazards.
Record and average temperatures in host cities ©
Heatwave: high risk in several organizing cities
In Paris, whether it is athletics (at the Stade de France), road cycling (at the Champs-Élysées for arrivals), the marathon (which will cover the emblematic sites of the capital), athletic walking and beach- volleyball (at the Champ-de-Mars) or even swimming (in open water at the Bassin de la Villette), all these events which take place outdoors will make the athletes completely dependent on the weather.
Paris and its region may have a temperate oceanic climate, but episodes of extreme heat are becoming more and more frequent there, due to global warming. The most significant is the heatwave of August 2003 when the thermometer exceeded 35°C for 9 consecutive days, with nighttime temperatures which did not fall below 22-25°C within the city limits. Such conditions can generate increased fatigue for athletes and pose logistical challenges for organizers if certain events must be anticipated or delayed.
In Lyon, Bordeaux and Saint-Étienne which will host the football events, the risk of exposure to high heat could be even greater and weigh significantly on the players. For example, the Lyon Bron station records on average more than 11 days of high heat (>30°C) in July and 10 in August, and 23.5 days of heat (>25°C) in July and 22.4 in August. This heat parameter is one of the risks well identified by the organizers. But, well anticipated does not mean without consequences. We remember the Athens 2004 games which were particularly affected by the heat, or those of Tokyo 2021. They were marked by temperatures between 30 and 40°C, and a very high humidity level, which had led to schedule changes for certain events.
Tropical nights: Mediterranean cities particularly exposed
Like Marseille, which will also host the sailing events, the city of Nice will host some football matches. For these two Mediterranean cities, it is the night-time temperatures that could be more difficult to bear.
Indeed, due to the proximity of the Mediterranean Sea, warm at this time (24-26°C on average), minimum temperatures do not really drop at night. In Marseille, the average minimum temperature is 19°C in July and August and 21°C in Nice, with frequent tropical nights (>20°C) and high humidity. These conditions could be an additional nuisance for the athletes. The heat can also be difficult to bear during the day, but less so than in other host cities, since the sea breezes tend to temper the air.
The North: department least exposed to heatwaves
The city of Lille will also host some football matches. However, the North is one of the departments hosting the Olympic Games which could be least exposed to the risk of a severe heat wave. There are only 2.5 days with temperatures above 30°C in July and 2.8 days in August. Nighttime temperatures average 14°C in July and August, which can allow athletes to better recover. However, Lille and its department are not immune to the risk of heatwaves, as in 2019 and 2020. The station recorded 41.5°C on 07/25/19 and 37.1°C on 08/ 08/2020. In the context of global warming, these events are likely to recur more frequently, but can only be anticipated ten days in advance.
Strong thunderstorms: a greater risk in the south
A strong storm is counted when a phenomenon such as hail (> 2 cm), a convective gust (> 90 km/h), a tornado and/or rain (> 50 mm/h) is noted.
The regions hosting the Olympics being those most exposed to these risks in July and August are Nouvelle-Aquitaine and Auvergne-Rhône-Alpes.
For example, the Loire department records eight days of strong storms per year, the majority of which occur in the heart of summer. For comparison, Paris is only subject to two days of strong storms per year and the Nord department, 4 days. These conditions can disrupt competitions, especially outdoor ones, such as athletics and cycling. In 2008, for the Beijing Olympics, storms caused delays in the athletics and tennis events and in 2016 in Rio, several sailing events were postponed due to violent storms.
Risk of postponement of swimming events in the event of a storm
Pollution of the Seine represents a major challenge in view of the Paris 2024 Olympic Games. Indeed, this global event plans open water swimming competitions and triathlon events in the famous Parisian river.
The quality of the water in the Seine is therefore a primary concern. However, in the event of a storm or rainy weather, the flow of the Seine will increase, which will not promote good water quality. The main risks associated with this pollution include the presence of pathogenic bacteria and harmful chemicals. Measures have been taken to improve this quality (cleaning, reduction of polluting discharges including the construction of a retention basin which should prevent the discharge of untreated water into the river) in the event of heavy rain. The heavy rains of recent months have not yet made it possible to achieve the necessary health regulations. Actions must be intensified to ensure that pollution levels are low enough to ensure safe competitions. The challenge is great, but essential for the success and integrity of the Paris 2024 Olympic Games. The swim of the Mayor of Paris Anne Hidalgo, which must illustrate the newfound quality of the waters of the Seine, has been scheduled for the week of July 15 .
Dry season in Tahiti for surfers
The surfing events will take place in French Polynesia, on the island of Tahiti, and will finally allow the Overseas Territories and their populations to be associated with the Olympic Games for the first time in history. The choice of Tahiti will give rise to an exceptional competition in a location, Teahupo’o, acclaimed by the world of surfing. The period corresponds to the dry season with only three days of rain on average in July and August. Good weather should therefore dominate during the competitions, and the risk of cyclones is completely eliminated, the season extending from December to April in this part of the Pacific. This period is also less subject to the discomfort of heat, due to a lower humidity level than in the wet season.
Faced with these climatic hazards, athletes and spectators will have to take certain precautions. Athletes will need to prepare well by adjusting their training and diet accordingly. For spectators, in the event of extreme heat, the organizers have provided easily accessible shaded areas and hydration points. Weather forecasts and potential alerts should be followed carefully. They will be done in particular by the organizers and emergency services, who will be on war footing to welcome the 15 million tourists in the capital alone.
Main weather hazards during the 2024 Olympics ©
