What actually changed in 2026
In December the ATP approved a uniform, science-based heat policy that mirrors what the WTA has long used. The rule hinges on Wet Bulb Globe Temperature, or WBGT, a metric that blends temperature, humidity, sun, and wind into one risk score. Think of WBGT as the sport’s heat speed limit: it tells referees when play must slow down and when it must stop, no guesswork. According to the ATP’s 2026 uniform heat policy, two thresholds matter for best-of-three singles:
- If WBGT hits 30.1 degrees Celsius in the first two sets, either player may request a 10-minute cooling break after set two. The break applies to both players, is supervised by medical staff, and coaching is permitted.
- If WBGT exceeds 32.2 degrees Celsius, play is suspended.
This season the rule covers ATP matches and aligns with the WTA approach, so mixed-team weeks and combined events will feel more consistent for players and coaches. For tactics around those triggers, see the ATP 2026 heat rule playbook.
Why WBGT matters on court
WBGT accounts for what the body feels and must dissipate, not just the number on your phone. A 33 Celsius cloudless afternoon in Sydney with low wind can be more dangerous than a slightly hotter but breezier evening. That matters for tennis because performance degrades as core temperature rises, reaction time slows, and decision-making suffers. The policy uses WBGT to trigger structured cooling before a player’s core temperature spirals into the zone where cramping, dizziness, or heat illness becomes likely.
United Cup 2026: the first proving ground
This year’s United Cup runs in early January in Perth and Sydney. Perth’s RAC Arena is an indoor venue with a retractable roof, so many day sessions there feel more controlled. Sydney’s Ken Rosewall Arena has a fabric roof that shades the court but remains open to warm, humid air, which means WBGT can climb rapidly during day sessions. With a severe heat pattern hitting much of Australia in early January, Sydney day ties have been the likeliest to push the new rule toward activation.
What have teams learned so far?
- Preparation is everything. Squads arrived with ice vests, cooled towels, insulated bottles, and slushy mixes packed in large coolers. On-court staff now move these tools with the players, so setup is immediate if a cooling break is triggered.
- Perth vs. Sydney microclimates. Players biking through warm-ups under Perth’s roof then flying to Sydney have commented on how the same 28 to 30 degree air feels much harsher on court when the sun is blasting the bowl and the wind dies. Coaches have started tracking WBGT from the morning onward and building if-then match plans for afternoon ties.
- Coaching in the heat break changes the chess. The 10-minute window is no longer a passive survival moment. It is a mini time-out with ice and a whiteboard. The best-prepared teams bring a precise, rehearsed script for those 10 minutes.
For late-point patterns in pressure moments, study our United Cup 2026 tiebreak blueprint.
Even if a match never crosses 30.1 WBGT, the mere possibility forces better planning. That alone has already shifted match prep across both tours.
Your new match-day plan under the heat rule
Here is a concrete, step-by-step framework for players and coaches. To turn these habits into training blocks, use our 14-day off-court training plan.
1) Acclimate the smart way
- Ten to fourteen days out: schedule 60 to 90 minutes of on-court work during local heat hours at least every other day. Ramp intensity, not just duration. Finish with short sprints so your first explosive move in competition does not shock your system.
- Add passive heat exposure: 20 to 30 minutes in a warm environment right after a moderate session, two to three times per week, to stimulate sweating adaptations without beating up your legs.
- Track perception. Use a simple 1 to 10 heat-strain rating after every session. Real acclimation shows up as the same work feeling easier at a given temperature.
2) Pre-cooling before you play
- Thirty minutes out: drink 300 to 500 milliliters of a cold sports drink or crushed-ice slushy. Aim for sodium around 500 to 700 milligrams per liter. If you are a salty sweater, push toward the higher end.
- Ten minutes out: don an ice vest for 5 to 8 minutes or place two ice towels across the neck and forearms. The goal is to step on court with a lower core temperature and head start your sweat.
- Clothing check: lightweight, light-colored kit, perforated cap, wristbands for sweat management, and a spare shirt and socks in a zip bag per set.
3) Hydration and fueling during play
- Baseline flow: 0.4 to 0.8 liters per hour is typical for tennis, but your sweat rate rules. Weigh yourself pre- and post-practice in similar heat to estimate loss. Replace 125 percent of the fluid lost over the next few hours.
- Sodium plan: at least 500 milligrams per liter during heavy sweating. If you routinely salt-stain your hat or shirt, consider 700 to 1,000 milligrams per liter.
- Carbohydrate plan: 30 to 45 grams per hour from drink, gels, or chews. Heat reduces gut tolerance, so trial your mix during practices before competition.
4) Cooling every changeover
- Ice towel on the neck and across the forearms. Rotate two towels in a cooler so one is always chilled.
- Use shade deliberately. Sit so your face and trunk are shaded. If there is a courtside fan, angle it across your torso.
- Breathe slow and deep. Three slow breaths before standing up can meaningfully reduce perceived effort.
Make the 10-minute cooling break a weapon
When WBGT hits 30.1 in the first two sets, either player can request the 10-minute break after set two. Coaching is permitted. Plan the break like a pit stop. Here is a minute-by-minute blueprint many teams are testing:
- Minutes 0 to 2: shoes off, socks off, shirt off. Sit in shade. Start sipping a pre-mixed cold bottle with sodium and light carbs. Avoid chugging.
- Minutes 2 to 6: cold shower or thorough cold-water dousing. If no shower is near, wrap an ice towel around the neck and underarms, then rotate to the forearms. Put on an ice vest for three minutes if available.
- Minutes 6 to 8: fuel top-up. Ten to twenty grams of quick carbs plus a small amount of fluid. Dry the hands fully. New socks and shirt on. Re-tape blisters if needed.
- Minutes 8 to 10: coaching huddle. Two adjustments max. One primary play pattern and one return tweak. Confirm first-service targets for the next two games. Agree on between-point pacing and breathing cues.
What to discuss with your coach in that window:
- Scoreboard-aware pacing. If you are serving first in the decider, use the full serve clock to recover on early games, then shorten between-point time when you feel momentum. If you are returning first, commit to making the opponent hit extra balls in that opening game to test their cooling.
- Serve plus one plan. The heat rule favors the player who can shorten points without rushing. Choose one serve target and one forehand or backhand lane you will repeat until the opponent solves it.
- Contingency for suspension. If WBGT feels like it could climb past 32.2, decide whether to raise intensity now to bank a lead or to hold a battery for a later restart.
Strings, balls, and the physics of hot air
Heat alters both your strings and the air your ball travels through. Plan your setup, not just your hydration.
- Tension mapping: hot, thin air can make the ball fly faster, but strings also lose tension quicker in heat. Two viable heat setups exist. Some players string 1 to 2 percent tighter to tame the livelier ball. Others drop 1 to 2 percent to increase spin and clearance when legs feel heavy. Test both in practice sets during the warmest hour and chart your unforced errors long vs. long plus depth.
- Gauge and material: a slightly thicker polyester or a hybrid with gut or a soft multi can keep control as temperature rises and contact degrades late in the match. Bring at least two frames with your heat setup ready.
- Ball behavior: expect fresh balls to jump off the court more in heat, then fluff after a few games if humidity is high. Plan your return position to start a half step deeper on new-ball games.
Pacing and tactic shifts that win in the heat
- Respect the serve clock. Use the full time after lung-busting rallies. That is legal and wise. Heat punishes impulsivity.
- Own the shade. If one baseline has more shade, adjust your return position slightly to buy extra seconds under cover between points.
- Shorten the pattern menu. Run your highest-value pattern until the opponent proves a counter. Heat takes options away; choose for your opponent by repeating your best play.
- Change heights and speeds. Slice backhands, body serves, short-angle forehands, and the timely serve-and-volley force the opponent to sprint less predictably and can keep their core temperature lower than endless corner-to-corner sprints.
- Target legs, not lines. On truly oppressive days, make the other player move first and often, but do it with margin and spin rather than line-licking drives.
Mental routines that protect performance
- Two-count reset. Before every return game in tough heat, take two deliberate breaths with a long exhale. Quiet your vision on the strings for one full second to narrow focus.
- Neutral self-talk. Replace “I am dying out here” with “This point, this play.” Keep language factual. Heat magnifies negative spirals.
- Symptom scan. Dizziness, chills, or confusion are red flags. Tell your coach or trainer immediately. No match is worth a serious heat illness.
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 rehearse this exact heat protocol and to build your breath, pacing, and decision routines into muscle memory.
What to watch for at the Australian Open later this month
The Australian Open has used its own heat stress scale since 2019 and refines it regularly. For context on how the tournament implements thresholds, umbrellas, misting, and potential roof closures, see this concise Australian Open heat stress scale explainer. Expect the event to be proactive on scheduling, with more night sessions on outside courts if a severe heat spell lingers.
Your scouting list for Melbourne:
- Threshold signals. Look for courtside monitors or announcements that the heat stress level has risen. When it does, expect more shade, longer time between points, and possible roof closures on main courts.
- Specialists in the heat. Players who thrive with short, explosive points and high first-serve percentages will have an edge. Those who commit to their heat break routine will turn the new rule into free momentum.
- Outside courts vs. roofed courts. The toughest conditions are often on mid-sized courts during midday. If you coach or parent a junior watching live, study those patterns. They mirror the real-world conditions your players will face all season.
Key planning note: qualifying typically runs the week before the main draw, and the 2026 main draw is slated for late January across a 15-day window. Plan your training to mimic those time windows and heat profiles.
A one-page checklist for coaches and parents
- Ten to fourteen days out: schedule three heat-acclimation sessions and two passive heat exposures.
- Pack list: two pre-cooled towels, one ice vest, two insulated bottles, a backup hat, three shirts and sock sets, blister kit, and two racquets strung for heat.
- Pre-match: 300 to 500 milliliters cold fluid with 500 to 700 milligrams sodium per liter; 10 to 20 grams quick carbs.
- In-match: 0.4 to 0.8 liters per hour; at least 500 milligrams sodium per liter; 30 to 45 grams carbs per hour.
- On changeovers: ice towel rotation, shade-first seating, three slow breaths before standing.
- Cooling break plan: minute-by-minute script taped in the bag, plus two tactical adjustments only. Rehearse it this week.
- String strategy: one frame plus 2 percent tension and one frame minus 2 percent tension tested in practice; choose based on feel and miss pattern.
The bottom line
The 2026 heat rule does not just add a pause; it rewrites how smart players and coaches prepare for Australia’s summer. Teams that treat WBGT as a tactical signal, not just a safety alarm, will win matches others lose to fatigue and indecision. Use the United Cup lessons to build your scripts now, then bring them to Melbourne when the heat and the stakes rise.
If you want a ready-made heat playbook, build it in OffCourt. OffCourt turns how you actually play into a personalized training plan, so your cooling, hydration, pacing, string setup, and mental routines are automatic when the thermometer climbs.
Train it, rehearse it, then execute when the ten-minute countdown starts.