ATP 2026 Heat Rule Playbook: WBGT Triggers, 10-Minute Breaks, and January Match Tactics

Why this rule changes January tennis

January in Australia has always been a gut check. Now it is also a chess match. Beginning in 2026, the ATP will use a Wet Bulb Globe Temperature trigger to allow a 10‑minute cooling break in best‑of‑three singles when heat stress reaches a defined threshold, and to suspend play when it climbs higher. For coaches, parents, and ambitious juniors, that turns heat from a background hazard into a tactical lever you can plan for. See the official breakdown in ATP announces new heat rule.

Two practical notes. First, the Australian Open is governed by Tennis Australia’s own Heat Stress Scale rather than ATP’s WBGT, and it has its own break and suspension logic. For a clear explainer of that system, see how the AO Heat Stress Scale works. Second, the United Cup is a combined event and will harmonize its operations with host venues and governing bodies. That means players can face slightly different metrics within the same January swing.

The rest of this piece is a practical playbook. For a deeper rules primer, pair this with our internal guide, ATP 2026 heat policy strategy, and for team events see the United Cup 2026 team guide.

The science in plain language: WBGT

WBGT is not just temperature. It blends air temperature, humidity, radiant heat from the sun, and wind. Imagine putting your body in a weather blender. If humidity is high, sweat does not evaporate as well, so your natural cooling is limited. If the sun is fierce, you absorb radiant heat like a dark court surface. Wind helps by moving sweat and heat away from your skin. WBGT rolls those factors into a single number that predicts how hard your body has to work to stay cool.

Why this matters to your tactics: WBGT moves during the day. It dips with cloud cover, climbs on still, bright afternoons, and often falls quickly after sunset. Treat WBGT like live scoreboard data. If conditions are rising toward the trigger late in the second set, the looming break becomes a weapon you can time and use.

What the 10‑minute break actually allows

The rule’s core features are simple and actionable.

• When the WBGT hits the trigger in set one or two, either player can request the 10‑minute cooling break after set two.
• The break applies to both players. No one stays out on court to hit serves while the other disappears.
• Players can hydrate, change clothes, take a cold shower, apply ice packs, and receive coaching, all under medical supervision.
• Play is suspended if WBGT exceeds the higher threshold. The referee resumes only when it drops.

Build your routines to use exactly what is available.

How this intersects with the Australian summer and United Cup

• Australian Open: Uses the AO Heat Stress Scale, a 1 to 5 index on dashboards around the site. At high levels the tournament can allow a time‑limited break and then suspend play or close roofs on stadium courts. This is a different decision tree from the ATP WBGT triggers, so players must be bilingual in heat policies.
• United Cup: Mixed event staged across Australian cities. Expect venue‑specific microclimates and schedule slots that run day to night. Team staff should track daily WBGT forecasts and venue shade patterns. Warm‑up and fueling windows must flex with match times.

Bottom line for January: you need a playbook that works across both systems. Plan for an ATP‑style second‑set break at tour events and a scale‑based call at Melbourne Park.

Build the foundation: acclimatization and pre‑cooling

Heat tolerance is trainable within two weeks. The body increases plasma volume, improves sweat response, and reduces heart rate at a given workload. Here is a simple calendar for a player arriving from a Northern Hemisphere winter.

• Days 1 to 3: Easy aerobic work for 30 to 45 minutes in the hottest safe part of the day. Finish with 10 minutes of light court movement. Goal is gentle exposure, not fitness gains.
• Days 4 to 7: Add controlled intervals on court. For example, 8 by 2‑minute rallies at match footwork pace with 1‑minute walk. Keep technical drills short and crisp.
• Days 8 to 12: Simulate match work. Two 30‑minute blocks that feel like real set intensity with full serve and return patterns. Monitor heart rate recovery at changeovers. Start testing your between‑point routine under heat stress.

Pre‑cooling matters on match day. The goal is to lower core temperature and skin temperature before you step on court, so you have more thermal headroom when the match starts.

• 20 to 30 minutes pre‑match: Drink a cold slushy or iced sports drink. Add ice to fluids and sip to tolerance. The cold fluid lowers thermal strain without bloating.
• 15 minutes pre‑match: Apply an ice towel across the neck and shoulders for 5 to 10 minutes. If a cooling vest is available, wear it during the walk to the court.
• 5 minutes pre‑match: Dry off and start a brisk dynamic warm‑up. Keep it short. The heavy lifting on body temperature was done by the cooling, not by overheating in the warm‑up.

Off‑court training is the most underused lever in tennis. Use your tracking data to identify whether you fade in longer rallies or after extended deuce games, then tailor pre‑cooling and pacing to your game profile.

Hydration and sodium: simple math you can use

Dehydration of 2 percent of body mass hurts decision making and increases perceived effort. You can get there fast in the Australian summer. Build a personal plan.

• Sweat rate test: Weigh before and after a 60‑minute practice in similar heat. Track every milliliter you drink. Every kilogram lost equals roughly one liter of sweat. Repeat twice to confirm.
• Baseline intake: Aim for 0.4 to 1.0 liters per hour in match conditions, adjusted by your measured sweat rate. Smaller sips at changeovers are easier on the gut than gulps at set breaks.
• Sodium plan: If you see heavy salt marks on clothing or get calf twitches late in sets, increase sodium content. Add electrolyte tablets or a higher sodium mix to reach 500 to 1000 milligrams per liter during hot matches, adjusted to your tolerance and sweat rate. Keep a lower sodium bottle and a higher sodium bottle in the bag and alternate based on feel.
• Post‑set rapid cooling: During the 10‑minute break, combine cold fluids with ice towels on the neck and inner thighs. Change into dry socks and a dry shirt to reduce skin irritation and improve evaporative cooling.

Set‑to‑set pacing with the new break in mind

The second set is now a hinge. How you manage effort from 3‑all to 5‑all can change the third set entirely.

• If you are down a break late in set two and the WBGT trigger has been reached, consider protecting legs and mind for the restart. Shorten points behind first serve. Serve to the body more to reduce return angles. Use the stretch of time until the break to conserve, not to chase low percentage winners.
• If you are up a break late in set two and the break is imminent, step on the gas to lock the set. Winning 6‑3 with lower mileage beats 7‑5 with a sprint finish before a cooling stop.
• If set two is tight and the break is almost certain, build a mini‑game plan for the first two return games after the restart. Players often come out of the cooling room with a different bounce. Expect a flurry of first‑serve bombs and a few short second serves as rhythm returns. Prepare two default patterns in your notes. For a structured restart plan, use our two‑week tiebreak training plan.

Serve and return patterns that survive heat

Heat rewards clarity. Long points, heavy recovery, and repeated explosive changes of direction add up. Design patterns that simplify choices and limit travel.

Serve patterns

• First serve: Raise your first‑serve percentage target by 3 to 5 points in hot spells. Hitting 64 percent at 120 miles per hour will beat 58 percent at 125 when your legs are baking.
• Body serve: Use it three times per game in heat, especially at 30‑all or deuce. It reduces the returner’s swing and keeps you in center court.
• Deuce side slider: In heat, slide wide only if you have a baked‑in plus‑one to the open court. Otherwise the recovery to the next ball is expensive. Choose a slicing serve that drags the return into your forehand and finish early.

Return patterns

• Block first serves back middle to neutralize. Treat this as a field position play. Depth over angle. Your goal is to get into a rally without sprinting two steps off court.
• On second serves, move up a half step to take time while avoiding a full pivot sprint. Aim at the server’s feet. Make them hit up and start slow.

Rally design

• Avoid mid‑court fiddling. Either attack with a single change of direction behind a good ball or reset deep and heavy to the middle third. Side to side patterns are costly in heat.
• Use height. When you feel your legs fading, add a meter of net clearance and a meter of depth. The ball travels long while you recover in two controlled steps.

Between‑point routines that lower body temperature

The 20 to 25 second space between points is your battery charger. Use it on purpose.

• Walk to the towel. Slow your exhale as you approach. This lowers breathing rate and helps parasympathetic recovery.
• Ice towel at changeovers on neck and under forearms. Keep it for 20 to 40 seconds, then remove to avoid skin vasoconstriction that traps heat.
• Shade discipline. Learn where shadows fall on your court at different times of day. Step into them every chance you get.
• Clothing checks. If your shirt is soaked and clinging, it is slowing evaporation. Change at every set break and during the cooling break.

Coaching inside the 10‑minute window

Because coaching is allowed during the ATP cooling break, arrive with a script. Do not improvise with adrenaline running.

A three‑phase checklist

1. First three minutes

   • Fluids: 300 to 500 milliliters of cold drink with sodium. Small sips.
   • Cooling: Ice towel to neck and thighs. Shoes off if feet feel hot spots. Dry socks ready.
   • Quick scan: Ask for dizziness, nausea, or cramping. If yes, slow everything down.

2. Middle four minutes

   • Tactical reset: Two bullet points only. For example, raise first‑serve percentage target and return two feet inside baseline on seconds. Write them on a small card.
   • Pattern call: Choose one serve play on each side and one second‑serve return play. Name them with short cues the player knows.

3. Final three minutes

   • Clothes: Dry shirt, dry wristbands, dry hat.
   • Mindset: One sentence. Example: Protect center. Win the first two points with first‑strike plays.
   • Re‑warm: Five band pulls, ten shadow swings, two quick skips. Walk to baseline with steady breathing.

Equipment and sideline setup

• Two bottles strategy: One higher sodium mix and one standard sports drink. Label them clearly.
• Cooling kit: Two ice towels in a small cooler bag, a spare hat, extra socks, small chamois cloth to dry hands before serves.
• Footwear: Choose lighter uppers that breathe well. Replace insoles if they take on water and heat.
• Grips and rosin: Heat turns palms to glass. Rotate new overgrips more often. Keep a small rosin bag or grip enhancer in the bag.

Scouting and scheduling

• Track WBGT forecasts, not just temperature. Many Australian host cities publish hourly heat stress forecasts in summer. Build a simple chart for the team and update each evening.
• Know court orientation. Morning sun and afternoon sun hit baselines differently. If a coin toss matters, choose the baseline with better early shade.
• If a match starts near the likely trigger time, front‑load your highest percentage plays for the last two games of set two. Steal a set while your opponent is in a holding pattern waiting for the break.

A practice template for the Australian summer

Use this 90‑minute plan three to five days before your first January match in heat. It is designed to rehearse both the conditions and the new rule.

• Warm‑up and pre‑cooling: 10 minutes dynamic plus 10 minutes of ice towel and cold fluid.
• Set one simulation: 25 minutes. Serve plus one and return plus one at 70 to 80 percent. Track first‑serve percentage and depth on the first ball after return.
• Short recovery: 5 minutes for fluid and shirt change. Walk in shade.
• Set two simulation: 25 minutes. Increase intensity to 85 percent. At minute 20 have a coach announce that the WBGT trigger has been reached and you will take a cooling break at the end of the set. Practice protecting legs for the last two games while holding serve with safe patterns.
• Cooling break drill: 10 minutes following the three‑phase checklist above. Practice the sequence exactly as you will on match day.
• Post‑break restart: 10 minutes. Execute your pre‑chosen serve and return patterns for the first two games. Emphasize first‑serve percentage and deep middle returns.
• Cool down: 5 to 10 minutes easy movement in shade and cold fluids.

What remains difference at the Australian Open

Do not assume the same numbers everywhere. The Australian Open’s Heat Stress Scale is a five‑level system that can trigger a 10‑minute break and, at the highest level, suspend play or close roofs. The metric is different from WBGT but the aim is the same. Your on‑court routines still apply. Know where your towel is, when to change clothes, and which two patterns you trust after a stoppage. The key is to prepare your body and your plan for a sudden pause and a sharp restart.

The January advantage: make heat your edge

Heat will still test everyone. The new ATP rule turns some of that test into structure you can use. The teams that treat WBGT like a tactical data point, that rehearse the 10‑minute break as if it were a tiebreak, and that build personal hydration and cooling plans will walk back on court fresher and clearer.

Your next steps

• Write your personal cooling break script and put it in your bag today.
• Run one full practice that includes a simulated second‑set trigger and a 10‑minute break.
• Measure your sweat rate once this week and once next week. Adjust sodium and fluid targets.
• On match day, set phone reminders for pre‑cooling steps at 30, 15, and 5 minutes before call.

Then go win the restart. If you want a personalized off‑court plan that adapts to how you actually play, build your January heat plan inside the app.