How Are French Open Players Dealing With the Paris Heat Wave? | WIREDSkip to main contentMenuSECURITYPOLITICSTHE BIG STORYBUSINESSSCIENCECULTUREREVIEWSMenuAccountAccountNewslettersSecurityPoliticsThe Big StoryBusinessScienceCultureReviewsChevronMoreExpandThe Big InterviewMagazineEventsWIRED InsiderWIRED ConsultingNewslettersPodcastsVideoLivestreamsMerchSearchSearchBrian KahnScienceMay 28, 2026 5:03 AMWhy It's Almost Too Hot to Play Tennis at the French Open 2026Meet the wet bulb globe temperature, the ominous measure that shows when it's more than just a heat wavePhotograph: Dan Istitene/Getty ImagesCommentLoaderSave StorySave this storyCommentLoaderSave StorySave this storyThe first week of the French Open has yielded as many major upsets (two) as people collapsing on the court due to sweltering conditions.While temperatures in Europe are extremely hot for this time of year, they aren’t Sahara-in-the-middle-of-summer hot. To truly understand why people on the court are struggling amid the heat, you need to look at an obscure measure known as the wet bulb globe temperature. Consider it a souped-up version of the adage “it’s not the heat, it’s the humidity” that’s best suited for gauging the impact of heat on human health.A ball girl nearly fainted during a first round match on Monday while men’s player Jakub Mensik keeled over on Roland Garros’ red clay on Thursday after a five-set match, saying his body "just turned off.” Players have spent time between games sitting in the shade and putting bags of ice on their heads and shoulders, all in an attempt to beat the oppressive heat.Temperatures have hovered in the low- to mid-90s (or low-30s for Celsius aficionados), due to a “heat dome”, a persistent area of high pressure that traps warm air and causes temperatures to rise. This is where the wet bulb globe temperature comes in.The metric “takes into account multiple aspects of the environmental conditions such as temperature, humidity, solar radiation, and wind,” says Rachel Cottle, a postdoctoral research fellow at Texas Health Presbyterian Hospital Dallas. “This is important because when we think about how stressful the environment is, we need to take into account all of these variables that may increase our risk for heat-related illnesses.”A wet bulb globe temperature of 86 degrees Fahrenheit (30 degrees Celsius) might not sound that bad, but it represents the start of the danger zone for human health. At that temperature, sweat doesn’t evaporate as efficiently as it does at lower temperatures. Cottle has conducted research showing that even healthy young people start to experience issues when the wet bulb temperature—a measure that focuses on humidity and temperature—reaches around 88 degrees Fahrenheit (31 degrees Celsius).“While there is still a limit for athletes, their greater cardiovascular fitness and potentially, being heat acclimated will result in them having higher limits than non-athletes and non-acclimated people,” said health researcher Kat Fisher. “Going to shade and cooling the body with ice can help lower core temperature and help limit a continuous rise in temperature.”Having better endurance isn’t all athletes have going when it comes to beating the heat. “Athletes and individuals who are fit sweat more which helps them cool off more. They also begin to sweat earlier, so their bodies can start to cool off sooner. So essentially, athletes are more efficient sweaters,” Cottle notes, while also underscoring even the most efficient sweaters walking among us mere mortals have their limits. Without ample rest and access to cooling, the risk of heatstroke or heart issues rises.The French Tennis Federation reportedly keeps two thermometers that can measure the wet bulb globe temperature on courts at Roland Garros, with plans in place to have extended breaks between sets or even cancel matches if they surpass a certain threshold. Wet bulb globe temperatures at the French Open haven’t reached these levels yet despite some matches taking place during the hottest times of the day on courts with no shade. But the health issues on the court have shown the risks, and temperatures are expected to be even higher in the coming days as the heat dome parked over the region intensifies.The other three Grand Slam tennis events—Wimbledon, the Australian Open and the US Open—have heat plans in place that allow players to take longer rests and cool off. All the events rely on wet bulb globe measurements to implement them.Research published in 2017 found that today’s wet bulb globe temperatures are likely to be the norm within 20 years for locations in the northern hemisphere. A subsequent global analysis found that northern India, China, northern Australia, Africa, Central America and Southeast Asia would all see a “disproportionate increase” in the wet bulb globe temperature, though. In those already-hot places, billions of people are particularly exposed to extreme heat whether due to a lack of cooling or having to work outside.Prolonged exposure to wet bulb temperatures of 95 degrees Fahrenheit (35 degrees Celsius) is the upper limit of what humans can survive, as sweat essentially stops evaporating. Even the hottest parts of the world haven’t seen that happen—yet. This is hardly an issue for premier tennis events only, but what’s happening on the courts at Roland Garros is a preview of the future.CommentsBack to topTriangleYou Might Also LikeHow to find us: Add WIRED.com to your preferred sources in GoogleHow the Canvas hack threatened thousands of schoolsBig Story: I've covered robots for years—this one is eerily lifelikeOrbs, saucers, and flashes on the moon—here’s what’s in the UFO filesTake our survey: What does “home” mean to you?Brian Kahn is a senior editor for WIRED’s science section. He has covered climate, weather, and energy for nearly 15 years. Prior to WIRED, he ran climate tech coverage for Bloomberg, where he edited award-winning journalism and ran the Green Daily flagship newsletter. You can reach him securely on Signal ... Read MoreSenior Editor, ScienceTopicsclimateweatherextreme weatherclimate changefranceSportsRead MoreThis Summer, the American Water Crisis Becomes RealConcern over water access are poised to consume summer in the US, as crises in Corpus Christi and across the Colorado River threaten to boil over.Molly TaftWhy the 2026 Hurricane Season Might Not Be That BadThe impending arrival of El Niño will help keep the number of storms low. But it only takes one landfall to create a catastrophe.Brian KahnTop AirDoctor Coupon Codes for June 2026Save up to $400 on top air purifiers and filters with verified AirDoctor promo codes and special offers for May 2026.Molly HigginsHow Wet Weather in Argentina Helped Fuel the Cruise Ship Hantavirus OutbreakClimate change is helping create conditions that are driving the rodent boom—dubbed a ratada—in Argentina.María de los Ángeles OrfilaMexico City Is Sinking. A Powerful NASA Satellite Just Revealed How FastA new NASA map shows how the sinking of Mexico City is uneven, with areas registering up to 2 centimeters per month.Fernanda GonzálezCalifornia’s Wildfire Season Is Already OveractiveMajor fires are threatening homes and ecologically sensitive areas following a hot, dry winter.Brian KahnA Fundamental Principle of Aeronautical Engineering Has Been OverturnedIt’s long been accepted that the smoother the surface, the lower the aerodynamic drag. That turns out not always to be the case.Ritsuko KawaiIf You’re a Serious Bowler, You Need to Know About Bowling Lane OilBowling centers apply oil to their lanes using a machine that works like a giant inkjet printer. The pattern in which it’s applied can change everything about how the ball travels.Ben DowsettWhat Should Be in Your Emergency Kit Before Disaster Strikes?We consulted preparedness experts and WIRED’s team of testers for the essential gear to keep on hand in case of wildfires, earthquakes, and lord knows what else.Matthew KorfhageTesting for ‘Bad Cholesterol’ Doesn’t Tell the Whole StoryThere’s a more accurate way of measuring who’s at risk for cholesterol-related health issues. So why don’t more doctors use it?Anna McKieAll Your Hantavirus Questions, Answered by an Infectious Disease ExpertHere’s what you need to know, from why the cruise ship outbreak won’t spark the next pandemic to how hantavirus spreads.Emily MullinThe Best Smart Sprinklers and Irrigation SystemsWe’ve tested almost a dozen options that handle everything from scheduling and weather changes to water conservation, so you don’t have to.Christopher NullWIRED is obsessed with what comes next. Through rigorous investigations and game-changing reporting, we tell stories that don’t just reflect the moment—they help create it. When you look back in 10, 20, even 50 years, WIRED will be the publication that led the story of the present, mapped the people, products, and ideas defining it, and explained how those forces forged the future. WIRED: For Future Reference.More From WIREDSubscribeNewslettersLivestreamsTravelFAQWIRED StaffWIRED EducationEditorial StandardsArchiveRSSSite MapAccessibility HelpReviews and GuidesReviewsBuying GuidesStreaming GuidesWearablesCouponsGift GuidesAdvertiseContact UsManage AccountJobsPress CenterCondé Nast StoreUser AgreementPrivacy PolicyYour California Privacy Rights© 2026 Condé Nast. All rights reserved. WIRED may earn a portion of sales from products that are purchased through our site as part of our Affiliate Partnerships with retailers. The material on this site may not be reproduced, distributed, transmitted, cached or otherwise used, except with the prior written permission of Condé Nast. Ad ChoicesSelect international siteUnited StatesLargeChevronItaliaJapónCzech Republic & SlovakiaFacebookXPinterestYouTubeInstagramTiktok

The challenges faced by French Open players during the heat wave necessitated an examination of the environmental conditions by employing the metric known as wet bulb globe temperature to accurately gauge the impact of extreme heat on human physiology, moving beyond simple ambient temperature readings. While temperatures in Europe were extremely high, understanding the struggle involved recognizing that the severity of the heat is compounded by humidity, which is why the wet bulb globe temperature is considered a superior measure for assessing environmental stress on human health. This metric incorporates multiple environmental variables, including temperature, humidity, solar radiation, and wind, as noted by Rachel Cottle.

The text details how this thermal stress translates into physical limitations for athletes. A wet bulb globe temperature of 86 degrees Fahrenheit (30 degrees Celsius) signals the beginning of a danger zone where sweat does not evaporate as efficiently as at lower temperatures. Research indicates that the threshold where general human health risks begin to increase due to environmental stress is reached around 88 degrees Fahrenheit (31 degrees Celsius). Although athletes benefit from greater cardiovascular fitness and potential heat acclimation, their limits are still constrained, and optimal conditions, including adequate rest and cooling, are essential to mitigate the rising risk of heatstroke or cardiac issues.

Furthermore, the physiological advantage athletes possess is that they are more efficient sweaters and begin cooling sooner than non-acclimated individuals, allowing them to manage heat exposure differently. Despite this efficiency, the risk remains high without sufficient rest and cooling resources. The French Tennis Federation is reportedly utilizing wet bulb globe temperature measurements on the courts at Roland Garros, with plans to implement extended breaks or match cancellations if set thresholds are met, although these levels had not yet been reached. This approach contrasts with other Grand Slam events, which also rely on these measurements for heat planning.

Globally, long-term climate analysis projects significant changes, suggesting a disproportionate increase in wet bulb globe temperatures in already hot regions such as northern India, China, northern Australia, Africa, Central America, and Southeast Asia. The text further establishes the absolute physical limit for human survival exposure to these conditions, noting that prolonged exposure to wet bulb temperatures of 95 degrees Fahrenheit (35 degrees Celsius) represents the point at which sweat essentially ceases evaporation, regardless of location. The experience of the players at Roland Garros serves as an acute preview of future environmental realities, underscoring the necessity of incorporating complex environmental metrics into sports management and public health planning.