What the new rule says, in plain English
Starting in the 2026 season, the ATP uses Wet Bulb Globe Temperature, or WBGT, to decide when extra heat protections start. In best-of-three singles, if the WBGT reaches 30.1 Celsius during the first two sets, either player can request a 10 minute cooling break after set two and the break applies to both players. If WBGT exceeds 32.2 Celsius, play stops until it drops. The break allows hydration, clothing changes, cooling methods, a quick shower if available, and coaching. See the official language and thresholds in the ATP’s new heat rule details.
Grand Slams have their own heat policies, so this rule covers ATP Tour events, not the majors. Still, the principles below help any player competing in hot conditions. For deeper context on training and scheduling, see our ATP 2026 heat rule playbook.
WBGT, decoded for coaches and parents
WBGT is different from the heat index you see on a weather app. It blends air temperature, humidity, sun intensity, and wind to estimate the heat stress on a working body on court. That makes it better for tennis, where direct sun and radiant heat matter. For a simple primer, read WBGT versus heat index explained. If you want more of the tennis angle, we break down WBGT triggers and cooling breaks.
You do not need your own WBGT device to coach smarter. Watch tournament displays, listen for supervisor announcements, and assume stress is higher than the heat index whenever the court bakes under full sun with little wind.
The coaching opportunity: a scripted 10 minute break
Treat the cooling break as a mini halftime. Bring a plan you can run step by step, not a vague "cool down and drink." Use this template and tailor it to your player, surface, and match state.
- Minute 0 to 2: Get out of the sun fast. Sit in shade, remove cap, place a cold towel across the back of the neck and over the forearms. Slow nasal inhale for four seconds, long exhale for six to eight seconds to drop heart rate. Shoes stay on unless you have a dry pair ready. If possible, lightly douse the head and neck with cool water.
- Minute 2 to 4: Fluids start. Take 200 to 300 milliliters of a cool electrolyte drink. Aim for 500 to 1,000 milligrams of sodium per liter. Heavy sweaters who get salt rings on hats can go higher within that range. Avoid chugging a full bottle at once.
- Minute 4 to 6: Clothing change. Dry shirt and wristbands are small changes that feel big. If available, a quick cool shower is ideal. Reapply a fresh cold towel to neck and squeeze cool water over the forearms again. This "cold near, cool far" approach targets high-blood-flow areas that help offload heat.
- Minute 6 to 8: Fuel. A small carb top up of 20 to 30 grams is enough. Think half a banana, a simple gel, or a few chews. Sip another 150 to 200 milliliters of drink.
- Minute 8 to 9: Tactical reset. Confirm the first two service patterns and the first return pattern after the restart. Choose a tempo target and a clear first-play intention, for example body serve to forehand, plus one ball deep middle.
- Minute 9 to 10: Mental cue. One short phrase the player repeats as they stand to return or serve, such as "Breathe and build" or "Legs first, then swing." Send them out with a plan for the first four points.
Coaching is allowed during this break, so assign roles. One person manages cooling tools and fluids. One person, often the coach, runs the tactical script. Keep language short and directive rather than open ended.
Your hot-day toolkit: what to pack and how to use it
You do not need a lab. You need a routine and the right tools within arm’s reach.
- Cooling towels: Store in a small soft cooler with ice and a little water. Drape across neck and forearms at every changeover, not just in the break.
- Two insulated bottles: One with electrolytes at 500 to 1,000 milligrams sodium per liter, one with cold water. Color code them so the player never confuses which is which.
- Ice slush: If permitted, a semi frozen sports drink cools faster than a cold liquid. Sip small amounts to avoid gut slosh.
- Extra shirts, socks, wristbands, and a dry hat: Swap any surface that traps sweat and slows evaporation.
- Skin lube or anti chafe for the collarbone, underarms, inner thighs, and socks. Friction skyrockets when sweat pools.
- Lightweight umbrella or portable shade if allowed between courts. Even a few minutes out of direct sun helps.
- Simple hand fan or battery fan for air movement when there is no wind.
Hydration and fueling, with numbers that work
Pre match
- The night before: Eat a normal carbohydrate forward dinner and add salty foods. Hydrate to pale yellow urine, not clear.
- Four hours pre match: Drink 5 to 7 milliliters per kilogram of body mass. For a 60 kilogram player, that is about 300 to 420 milliliters. Add sodium if they are a heavy sweater.
- One to two hours pre match: If urine is still dark or you have not voided, drink another 3 to 5 milliliters per kilogram.
During play
- At each changeover: 150 to 250 milliliters of fluids, alternating electrolyte drink and water, or mixing both if the drink is not too sweet. Adjust volume to conditions and gut comfort.
- Sodium: Typical match targets are 300 to 800 milligrams per hour. Heavy sweaters may need 800 to 1,200 milligrams per hour. The safe ceiling is individual, so test in practice and watch for stomach distress.
- Carbs: 30 to 60 grams per hour in hot matches. Pick easy options your player tolerates when breathing hard.
- Do not overdrink. A simple check is to weigh before and after. Try to finish within 2 percent of starting body mass. If you lose more than that, add volume and sodium next time. If you gain weight, drink less next time and increase salt concentration.
Post match
- Replace 125 to 150 percent of the fluid lost over the next 2 to 4 hours. Add salty food and a balanced meal with protein and carbs.
Heat-aware tactics that win points without bleeding sweat
Hot matches reward clarity and economy. That means defined patterns, controlled geometry, and a serve plus one plan that travels. For examples drawn from pro match plans, study how the WBGT rule changed the game.
Serve
- Prioritize first serve percentage over pace. Hitting 5 percent more first serves saves two or three high cost return games later.
- Body serve early in games to shrink the opponent’s strike window and curb their swing speed. Follow with a first ball deep middle to avoid giving away angles.
- If your player owns a kick serve, use it selectively when the sun is high. The extra bounce can win short errors without a full sprint exchange.
Return
- Back up a half step on second serve returns to reduce reaction stress. Aim down the middle third to start neutral, then play plus one with legs under control.
- On first serve returns in heat, designate one automatic bailout: deep crosscourt with margin. Remove decision load.
Rally geometry
- Middle third is your friend. Balls down the center reduce angles and lower lateral meters. Teach this as a choice, not a retreat.
- Take the ball early on attackable heights, but only if the feet are set. Early timing without stable legs is a false shortcut.
- When extended, float a neutralizing ball high and deep rather than force a lower percentage counter. You are buying back breath and time.
Net play
- Encourage purposeful forays forward. One clean volley can replace six baseline strikes when legs are heavy.
- Coach a simple finishing map: approach to backhand, volley deep middle, cover line first.
Changeups
- Sparing use of drop shots and short angles makes sense if the opponent’s legs look rubbery. Do not build a diet around these if your player is overheating doing the chasing.
Tempo, between point routines, and using the clock
With the serve clock at 25 seconds, tempo is a lever. Teach a consistent between point routine that fills most of the allowed time without flirting with a time violation.
A simple four step routine fits heat days:
- Square: Face the back fence, square the shoulders, and take three long breaths. Eyes off the scoreboard.
- Sip: Small drink, one or two mouthfuls only. Electrolyte first, then water on the next changeover.
- Shade: Sit or stand in shade, towel to neck and forearms. Rewet if dry.
- Script: Say the next play out loud. Example for a returner: "Backhand middle, two deep, look line."
If a rally was brutal, walk a touch slower to the towel, then to the line, still inside the rules. Legal time, used well, is free recovery.
Match management: the first game after the break
Expect the restart to feel strange. Opponents who have not trained for a cooling break often come out flat or scattered. Plan an assertive but not reckless open.
- Server plan: High percentage first ball to a conservative target, then one committed plus one. Think serve body, forehand deep middle.
- Returner plan: Get the first return deep middle to deny angles, then look to volley if the ball sits up.
- Coaching tip: Reinforce one thing only, not five. The right cue beats a rambling speech.
Training to handle heat without breaking down
Acclimatization is not punishment. It is a short block where your athlete learns to sweat earlier and more efficiently and to feel less strain at a given workload.
- Seven to ten day ramp. Begin with 45 to 60 minutes at easy to moderate intensity in the late morning heat, then build to 75 to 90 minutes. Keep movement quality high, not ragged.
- Separate speed from heat. Do pure speed and skill work in cooler windows. Use the heat block for steady footwork, rally drills, and patterning.
- Monitor. Record session start weight, finish weight, and fluid intake to see what the body actually needs. Use the data to set match hydration targets.
Off court support matters too. Sleep is a cooling process. So is recovery nutrition. 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. Use it to program heat acclimatization, breathing work, and mental cueing into the same calendar your athlete already lives by.
Club and junior takeaways for this summer
Most junior and club events will not read out WBGT courtside, but the body does not care who sponsors the match. Bring the same playbook.
- Pack the kit: electrolyte bottle, water bottle, cooling towel, extra shirts and wristbands, small soft cooler with ice, simple carbs.
- Pace the warm up: Shorten the on court warm up when the sun is brutal. Save energy for points that count.
- Win the shade: On side choice, pick the baseline with more shade if there is any. Stand where you get the most shadow between points.
- Use the rules: Take the full allowed time between points and at changeovers. Ask for the towel early and often.
- Watch for signs: Headache, goosebumps in heat, nausea, dizziness. Stop and seek help. Nothing about junior tennis is worth a medical emergency.
A quick checklist you can print
Before the match
- Hydrate to pale yellow, eat salty foods, and pack two bottles
- Pre plan first serve and return patterns for heat
- Pack cooling towel, extra kit, small cooler, simple carbs
During the match
- At each changeover: sip 150 to 250 milliliters, cool neck and forearms
- Stick to middle-third rally geometry unless the ball is short
- Use the full between point time with a four step routine
Cooling break
- Minute by minute script for cooling, hydration, clothing, tactics
- One phrase cue, one serve play, one return play
After the match
- Replace 125 to 150 percent of lost fluid, include salty food
- Log weights and fluids, review what worked and what did not
The bottom line
The ATP’s 2026 WBGT based rule turns hot days from chaos into a system. Players and coaches who treat the 10 minute cooling break as a skill win more second sets and close more thirds. The ones who plan hydration and cooling like a pre match string job last longer and think clearer when everyone else is foggy.
Build your heat checklist now. Script the break. Practice your between point routine. Test your drinks and sodium. Program your acclimatization with OffCourt, then show up this summer with a plan and the tools to execute it. Hot days will still be hard, but they will not be a surprise.