The new heat reality in tennis
From January 2026, the ATP will run matches using Wet Bulb Globe Temperature (WBGT), a heat-stress index that blends temperature, humidity, radiant heat, and wind. If readings hit 30.1°C (about 86°F) during the first two sets of best-of-three singles, either player can request a supervised 10 minute cooling break after set two. If WBGT exceeds 32.2°C (about 90°F), play will be suspended. During the break, players can hydrate, change clothing, shower, and receive coaching. This is a shift from local discretion to clear triggers that let teams plan for the moments that decide results, as noted in a Reuters report on the policy.
Grand Slam events will continue to apply their own heat policies, and several governing bodies already use WBGT-based thresholds. For a fuller rules overview, see our internal guide, deep dive on the rule.
WBGT, explained like a courtside coach
Think of WBGT as the on-court equivalent of an opponent’s scouting report. Regular temperature is just the score. WBGT is the full match context that accounts for what it actually feels like on a sunlit hardcourt. A WBGT reading of 30.1°C will often feel hotter than the air temperature in your weather app because it includes solar load and humidity. The International Tennis Federation uses WBGT to trigger cooling measures and explains thresholds and timing in its ITF explanation of WBGT triggers.
For a coach, the practical use of WBGT is twofold. First, you can predict when a break is likely in a match and pace your physical and tactical plan to hit that window with energy in reserve. Second, you can build training that teaches athletes to function at that stress level rather than fear it.
A 14 day heat acclimation block that works
Heat acclimation changes physiology in your favor. Sweat starts earlier and flows more, which improves evaporative cooling. Heart rate at a given pace drops. Core temperature rises less during similar workloads. The adaptation comes from repeated exposures, planned hydration, and enough recovery to keep progressing.
Here is a practical template for juniors and pros. Adjust volumes to age and training age.
- Days 1 to 3: 45 to 60 minutes of low to moderate intensity tennis or conditioning in a warm environment. Aim for the same time of day you expect to compete. Finish with 15 to 20 minutes of easy bike or jog in the heat. End with 15 to 20 minutes of passive heat, either a sauna at a comfortable setting or a hot bath up to mid torso. Keep intensity conversational.
- Days 4 to 6: 60 to 75 minutes on court with structured drills that create steady work, not constant sprinting. Examples include cross court lanes with two up, two back, or serve plus first ball patterns to targets. Keep rest short. Add 20 to 30 minutes of passive heat after, as above.
- Days 7 to 10: Push to 75 to 90 minutes on court with point construction and light sets. Keep shot quality high. Between sets, rehearse your cooling routine. Use ice towels and the fluid strategy you intend to employ in competition.
- Days 11 to 12: Two days that mimic competition. Same warm up, same start time, same timing of changeovers. Use your break routine after the second set if you are practicing best of three.
- Days 13 to 14: Taper the volume by 30 to 40 percent while keeping the timing and routines. Sleep and hydration take priority.
Metrics to track every morning: body mass after voiding, urine color, resting heart rate, and how you feel out of 10. A consistent drop in body mass of more than 1 percent and a darker urine color means you are underhydrated. A higher resting heart rate with flat mood is a cue to lower the load that day.
For indoor programs in winter, you can still build heat fitness. Use overdressing during easy bike rides, add a hot bath post session, and schedule longer rallies with minimal rest to simulate thermal stress. The rule is modest heat plus consistency, not a single brutal sweat session.
For travel timing and load management during long seasons, see our internal year-round performance playbook.
Hydration and electrolyte strategy that scales from club to pro
Hydration should be planned, not panicked. Even small water deficits make the court feel longer and your mind less precise. Build your match plan off pre match weighing and sweat rate estimates.
- Pre match: Drink 5 to 7 ml/kg of body mass in the 2 to 3 hours before play. For a 70 kg player that is about 350 to 500 ml. If urine is still dark 60 minutes out, add another 3 to 5 ml/kg.
- On court: Aim for 0.4 to 0.8 liters per hour, split into sips at each changeover. In extreme heat many players need the high end of that range.
- Electrolytes: Use 600 to 1000 mg sodium per liter of fluid. Heavy and salty sweaters can go to 1200 to 1500 mg per liter.
- Carbohydrates: Plan 30 to 60 g per hour for matches longer than 90 minutes.
- Post match: Weigh in again. Each kilogram lost equals roughly one liter of fluid. Replace 125 to 150 percent of that loss across the next 4 hours with sodium present in the fluid or food.
A do-it-yourself bottle that works for many: 500 ml water, 500 ml sports drink, a pinch of extra salt if you are a heavy sweater, and a squeeze of citrus to taste. Test everything in practice before match day.
Pre cooling and the new supervised break
You can lower strain before you strike the first ball. Use one of these pre cooling options 30 to 45 minutes before the match.
- Ice slurry: Slowly drink 300 to 600 ml of a half ice, half sports drink mix.
- Cooling vest: Wear a phase change vest for 10 to 15 minutes during your final walkthrough and visualization.
- Cold shower: Two to three minutes of cool water lowers skin temperature and makes the first games feel easier.
Now add the new 10 minute supervised break after the second set when WBGT hits 30.1°C during one of the opening two sets. Practice this sequence.
- Sit and breathe: 4 count inhale through the nose, 6 count exhale through the mouth for one minute while a coach or teammate sets the station.
- Ice towels: One around the neck and one on the quads or calves. Rotate every 60 to 90 seconds. Wipe sweat before reapplying so the towel can actually cool.
- Fluids and fuel: 300 to 500 ml of your drink. If cramping risk is high, use the higher sodium concentration. If energy is low, add a gel with water.
- Clothing reset: Change shirt, hat, wristbands, and socks. Dry skin cools better than drenched fabric.
- Brief coaching: One clear tactical priority for the next three games. Coaching is permitted under this new break. For tactical frameworks, see our internal guide on off-court coaching and AI.
If WBGT exceeds 32.2°C, play will stop. You will return later with a new warm up and a chance to mentally reset. If you are nearing the threshold, protect your serve games and apply scoreboard pressure on return without forcing low percentage shots.
Between set checklists to reduce errors
Heat drains decision making. A short checklist keeps you from drifting.
Physical
- Sip 150 to 250 ml of fluid each changeover. Alternate between water and your sports drink to taste.
- Cool skin at key points: neck, forearms, inner elbows, behind knees.
- Reset grip and feet: dry your hands, add rosin if you use it, and change overgrips before they get slick. Swap socks if they are heavy with sweat.
Mental
- One pattern you will hunt on serve for the next two games. Example: wide slider in the ad court, forehand to deuce open court.
- One return intention. Example: block deep middle on first serve, take a step back to buy time if the ball is flying in the heat.
- One tempo cue. Example: use most of the serve clock without rushing, then move quickly after you win a long rally to show presence.
Gear that keeps you cooler and in control
Climate smart apparel is performance gear, not just comfort.
- Fabric: Light colored, open mesh or micro perforated tops that move sweat off skin. Prioritize breathability over compression on the hottest days.
- Headwear: A light hat with mesh panels and a dark underbill to reduce glare. A thin sweatband under the hat can keep sunscreen out of your eyes.
- Socks and shoes: Moisture wicking socks with strategic cushioning reduce blister risk when feet swell. Loosen laces one eyelet for the first few games, then retighten.
- Cooling tools: White towels that take ice well, a small battery fan in your bag, and a collapsible soft cooler with ice packs. Phase change cooling vests can be used during warm ups and the supervised break when permitted.
- Eyewear: Polarized lenses with venting help prevent fogging when you come off changeovers.
- Strings: In fast, hot conditions, bump tension up by 0.5 to 1 kilogram (about 1 to 2 lb) for more control. If you play full polyester, consider a hybrid with a slightly thicker gauge in the mains or a stiffer cross for control without overtightening.
- Monitoring: A handheld heat stress meter can help coaches replicate match conditions in training. Your phone’s weather app is not enough on a sun baked hardcourt at 2 pm.
Match tactics for high heat
Hot conditions often play faster. Balls feel livelier, and legs feel heavier late. Blend your tactics to conserve fuel while applying pressure.
Serve
- Location over raw pace. Hit more first serves to corners to earn short replies.
- Use body serves to jam opponents who are backing up to buy time in the heat.
- Keep a consistent pre serve routine without extra bounces or fidgeting that add fatigue.
Return
- Take a half step back on first serve returns if the ball is jumping. Your goal is depth and height, not winners.
- On second serves, pick one forehand pattern and hunt it. The decision saves energy.
Baseline patterns
- More vertical, less horizontal. Drive deep through the middle to reduce court coverage. Shift to the corner only when you have space.
- Use the slice to change spin and pace without large swings. Short hop your slice to keep it low on hot, bouncy courts.
- Bring the net in. Finish with swing volleys or conventional volleys to end rallies before they become drainers.
Tempo and energy
- Use the full time allowed at changeovers and between points. Sit, breathe, dry, sip, reset.
- After a grinder rally, control the next point with a first strike play. If you lose one, buy time with a deep return and high margin rally ball.
Coaching and scheduling for juniors
Coaches and parents carry the duty of care. Build clear rules into your program.
- Training windows: On days when WBGT approaches 30°C, schedule hard work early morning or later afternoon. Midday becomes skill or serve practice under shade.
- Non negotiables: No practice without a personal water bottle and a hat. No match play if a player has a fever or gastrointestinal illness within 48 hours.
- Red flags: Dizziness, headache, stop start cramping, or a sense that the court is tilting. Pull the player, cool, and hydrate. Do not send them back out.
- Tournament prep: Arrive 48 to 72 hours before events in hotter climates to adjust sleep and food timing. Do short hits at venue time of day rather than long hits at odd hours.
How OffCourt.app can help you heat proof your season
Off court training is the most underused lever in tennis. OffCourt unlocks it with personalized physical and mental programs built from how you actually play. Inside OffCourt.app you can build a two week acclimation block that matches your calendar, set hydration reminders tied to your weigh ins, and save your between set checklist as an on court prompt. Coaches can push templates to their squads and collect post match data to refine the plan for the next hot week.
Practice scenarios to rehearse now
- Simulated supervised break: After two practice sets outdoors, stop for 10 minutes and run your five step pit stop exactly. Record how much fluid you take, what towels you use, and how quickly you stop sweating once the towel is on.
- Three gear tests in one week: Rotate shirts, hats, and socks to discover which combinations stay light. Note any chafing and adjust.
- Tension ladder: Practice with your normal string setup, then 0.5 kg higher two days later, then 1 kg higher two more days later. Choose based on control under heat, not just feel.
- Tactical constraint set: You must finish at net twice per game on serve. Or you must open three return games with a deep middle block. Find what conserves energy and wins points on the day.
What this policy means for the sport
The structured break at 30.1°C and automatic suspension above 32.2°C reward preparation. Players and teams who treat heat as a skill to train will gain a steadier heart rate, fewer decision errors, and a steadier second serve percentage late in sets. Event staff will align shade, mist, and scheduling with WBGT forecasts. Junior programs will adopt simplified versions of the thresholds. All of this moves tennis from vague “it is hot” judgments to a shared language of risk and readiness. For a broader strategy context, review our internal deep dive on the rule.
Your next steps
- Pick a target tournament that is likely to be hot. Put the 14 day acclimation block on your calendar now.
- Build your hydration plan and bottle recipe. Test it in at least two full practice matches.
- Script your 10 minute pit stop and rehearse it twice before your next event.
- Audit your gear bag for heat. Add ice towels, spare socks, and a pocket fan.
- Coaches, turn this article into a team protocol and hold a walkthrough.
Heat will decide matches in 2026. The rules tell you exactly when the critical moments arrive. Build your plan now, rehearse it, and treat extreme conditions as a competitive advantage you can train.