For decades, clay courts have been associated with long rallies, high bounces and physically draining tennis. But at this year’s French Open, players have repeatedly said Roland Garros is playing faster than usual. The reason is not a change in balls or court construction alone — it is the weather.
Paris is currently experiencing an unusually intense early-summer heatwave, with temperatures crossing 35°C during the opening week of the tournament. Groundskeepers say the conditions are unlike anything they have dealt with in late May.
“What we’re experiencing is unprecedented,” Philippe Vaillant, head of court maintenance at Roland Garros, told the Associated Press. “Even the weather services say it themselves: it’s unprecedented to have temperatures this high for such a long period at this time of year.”
The heat is fundamentally altering how clay behaves.
Why hot weather changes clay courts
Clay courts are moisture-dependent surfaces. Unlike hard courts, their playing characteristics are directly tied to how much water is retained beneath the top layer of crushed brick.
When temperatures rise sharply, moisture evaporates faster. The surface becomes drier and harder, which changes the speed and bounce of the ball. Players at Roland Garros have already noticed the difference.
World No. 1 Aryna Sabalenka said the conditions were “boiling hot” and that “balls are flying, everything is much faster.”
Traditionally, clay slows the ball down because moisture creates more friction between the surface and the ball. But dry clay reduces that resistance. The bounce becomes quicker and lower, favouring aggressive baseline hitting over attritional rallying.
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The shift is significant because Roland Garros has historically been the slowest Grand Slam surface. This year, players are increasingly comparing conditions to hard courts during afternoon sessions.
The science beneath the red clay
What appears to spectators as a simple layer of red dirt is actually a complex five-layer structure nearly 80 centimetres deep.
At Roland Garros, the courts are built using large foundation stones, gravel, volcanic rock residue, compacted limestone, and finally a thin layer of crushed red brick.
According to Vaillant, the limestone layer is the most critical component because it retains moisture and provides structural stability. The red brick layer is mainly cosmetic and helps players slide. If the limestone dries out excessively, the court can crack. More importantly, the surface becomes dangerously slippery. Vaillant compared overly dry courts to an ice rink, warning that players could lose footing while sliding into shots.
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“The crushed brick layer is 3 to 5 millimetres thick,” Vaillant explained. “The most important part is the limestone layer underneath. That’s the actual playing foundation. This limestone layer must remain moist at all times. It’s compacted crushed stone maintained through water supply. If we let it dry out too much, the courts could crack.”
The red brick layer, meanwhile, serves a different purpose.
“The crushed brick is mainly there for colour and as a material that provides some sliding ability and an important visual contrast, since the limestone is almost white,” Vaillant said.
How Roland Garros is keeping the courts alive
To combat the heat, tournament staff have dramatically altered maintenance routines. “We’re forced to water the courts a little more, of course,” Vaillant said.
Normally, clay courts are watered at fixed intervals. This year, groundskeepers are soaking the courts every evening to replenish moisture deep beneath the surface. During matches, courts are also being lightly watered between sets — something rarely required under standard French Open conditions.
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Another key tool is calcium chloride, a salt compound spread across the courts in flake form each morning. “Which is basically just salt,” Vaillant said. “We spread it over the courts in flake form in the morning. It melts on contact with water and helps retain surface moisture.”
The compound slows evaporation and helps the courts retain consistency through long matches played in direct sun. Groundskeepers say the substance effectively “reactivates” moisture in the crushed brick layer during the day.
The maintenance operation is massive. Around 200 groundskeepers are working across 18 competition courts and 15 practice courts during the tournament.
Why the courts have not deteriorated further
Ironically, heavy rainfall earlier in May may have prevented a larger problem. “We were able to let the rain do its job,” Vaillant said. “It recharged all our water-retaining layers.”
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That reserve has helped the surface survive several consecutive days of extreme temperatures without severe cracking. Without those earlier rains, the courts may have dried out far more aggressively.
