What changed on December 16 and why it matters
On December 16, 2025 the men’s tour confirmed a new extreme heat policy for 2026 that will shape how matches unfold and how players prepare. The rule uses Wet Bulb Globe Temperature, known as WBGT, to decide when additional cooling and stoppages are required. If WBGT reaches 30.1 degrees Celsius during the first two sets of a best of three singles match, either player may trigger a supervised 10 minute cooling break after the second set. If WBGT exceeds 32.2 degrees Celsius, play is suspended until conditions improve. These thresholds will be part of every ATP tournament in 2026. See the ATP's 2026 extreme heat rule and this Reuters report on new policy.
The ATP has aligned this framework with approaches already seen on the women’s tour and at some majors, where WBGT or similar indices guide heat management. The key difference for 2026 is clarity. Players, coaches, and officials now share specific numbers rather than relying on local discretion. That precision creates new strategic beats inside a match that can be trained and exploited. For a deeper primer on thresholds and matchcraft, read our guide to WBGT thresholds and tactics.
WBGT in plain language
WBGT blends air temperature with humidity, radiant heat, and airflow. Think of it as what the body actually feels rather than what a standard thermometer reads. Concrete courts absorb and re-emit heat, dark backdrops radiate it, and light winds or heavy humidity can make sweat less effective. A WBGT of 30.1 degrees means more heat stress than a dry 30.1 degree day in the shade.
Two thresholds now drive tactics:
- 30.1 degrees WBGT: a 10 minute cooling break may be taken after set two.
- 32.2 degrees WBGT: play stops until conditions improve.
These numbers are the new tide tables. Plan your day around them and you will conserve energy when others leak it.
The new rhythm of a best of three
The 10 minute cooling break after set two turns the third set into a fresh chapter. Expect more hard resets in momentum, more players switching string setups or shoes during the pause, and more targeted fueling just before the deciding set begins.
Set one: gather data without overcooking
- Play with a clean margin and map the opponent’s heat habits.
- Track how quickly they towel, whether their toss drifts in wind, and whether footwork shortens late in games.
Set two: manage the throttle
- If WBGT is rising toward 30.1 degrees, plan for a likely long pause.
- Up a break: slow cadence between points within the rules to avoid overheating.
- Down a break: create short, explosive plays, then buy recovery with deliberate between point routines.
Cooling break: treat it like a mini half time
- Change into a dry kit, apply ice towels to neck and thighs, and take a brief shower if available.
- Sip a pre-mixed bottle with sodium and carbohydrate. Keep total fluid reasonable to avoid sloshing.
- Receive one or two coaching cues at most.
Set three: start with a rehearsed pattern
- Open with a serve and first ball sequence you trained for this exact moment.
- A strong first hold matters more in heat because every early sprint taxes an opponent who may not have cooled effectively.
Tournament officials will still suspend play above the 32.2 degree mark, which means the final stretch of some afternoon matches may bounce between shade delays, cloud cover, and resumed play. Teams that script those oscillations keep quality high when others get ragged. For specific restart cues, study our cooling break playbook.
Off season heat acclimation that actually works
Heat tolerance is trainable. Done right, it can improve plasma volume, heart rate control, and sweat rate. Done poorly, it just makes you tired. Use this four week progression as a template. Adjust sessions to age and baseline fitness, and use medical discretion if you have underlying conditions.
Week 1: build the foundation
- 4 aerobic sessions at 60 to 70 percent of max heart rate in a warm environment, 35 to 45 minutes.
- 2 on court sessions with a hot finish: play or drill in the morning, then add 15 minutes of post session cycling in a warm room.
- Goal markers: consistent easy pace, no more than 1.5 percent body mass loss, light straw colored urine by the next morning.
Week 2: consolidate
- 3 aerobic sessions at the same intensity, now 45 to 55 minutes.
- 2 on court sessions with 2 short heat intervals, such as 8 minutes corner to corner on a ball machine, then 4 minutes shade and fluid, repeat once.
- 1 recovery day with mobility and a short walk.
Week 3: specific stress
- 2 aerobic sessions at 60 to 70 percent max heart rate, 45 to 55 minutes.
- 2 on court sessions that simulate hot match play with serve plus one patterns creating 6 to 10 ball rallies.
- 1 fitness session alternating strength blocks and 5 minute heat spins on a bike to train transitions.
Week 4: sharpen and taper
- 2 match play sessions, keep total duration to 75 to 90 minutes.
- 2 short aerobic sessions in heat, 30 to 40 minutes, to maintain adaptations without large fatigue.
- Finish with a full practice match in conditions similar to your first tournament.
By week three you should see lower heart rates at the same work, faster sweat onset, and less perceived strain. If these markers do not move, sleep or hydration may be the limiter. If you prefer a shorter ramp, try our 10 day WBGT acclimation plan.
Hydration and sodium that withstand the third set
Aim for euhydration, not overdrinking. A simple sweat test works: weigh yourself before and after a hot session. Each kilogram lost is roughly one liter of fluid. The goal is to limit body mass loss to under 2 percent, then replace about 125 percent of that loss over the next four to six hours. Include sodium, since sweat removes fluid and salt in variable amounts. The National Athletic Trainers’ Association position statement on heat illness outlines principles that support individualized fluid and sodium strategies.
Practical targets for tennis in the heat
- Pre match: 3 to 5 milliliters per kilogram of body mass in the 2 to 3 hours before play, with sodium in meal and drink.
- During play: 0.4 to 0.8 liters per hour, adjusted by body size, match pace, and conditions. Use your sweat test to personalize.
- Sodium: 300 to 600 milligrams per liter is a reasonable starting range, with higher needs for heavy and salty sweaters.
- Carbohydrate: 30 to 60 grams per hour, split between drink and simple bites. Test combinations in practice, not on match day.
For cramps, identify the driver. Some cramps are neuromuscular fatigue, others relate to sodium deficit. Stretch the affected muscle and sip a higher sodium drink if salt loss is likely. Build a pattern that keeps you in a steady zone long before cramp risk rises.
Between point pacing that cools without wasting time
You cannot change the shot clock, but you can change what happens inside it. In heat, the goal is to drive heat out of the core without signaling panic.
- Walk to the towel with purpose after long points, not after every ball. Over toweling adds time on feet in the sun.
- Exhale deliberately while walking to downshift heart rate. Two long exhales through pursed lips help more than you think.
- Reset your grip often. Switch to a dry overgrip whenever the handle feels slick to avoid excess forearm squeeze.
- Use micro cooling. Place an ice towel across the back of the neck for 5 to 7 seconds during changeovers. Avoid drenching your shirt mid set unless you have airflow, since evaporative cooling requires air movement.
Equipment tweaks that pay off in heat
Strings
- Expect lower stringbed stiffness during hot and humid play. Polyester can feel several pounds looser as temperature rises.
- Full polyester hitters can string 1 to 2 pounds higher before known hot events to keep launch angle consistent.
- In hybrids with natural gut mains, leave tension unchanged but expect a livelier response. A slightly thicker gauge can stabilize control.
Overgrips and handle care
- Rotate overgrips more often in heat, ideally every set.
- Cotton undergrips or leather absorb more moisture but add a small amount of weight. Test ahead of time.
- Keep a small rosin bag or liquid tack in your bag and apply on changeovers only.
Shoes, socks, and clothing
- Choose a breathable upper for outdoor hard courts. If you need stability, use a firmer insole rather than a fully armored shoe.
- Double socking with a thin liner can reduce slippage and prevent hot spots.
- Wear light colored, loose fit tops that allow airflow. A cap with a dark underbill reduces glare. Use a matte finish sunscreen to avoid a greasy grip.
Match strategy to leverage momentum swings
Heat turns neutral patterns into advantage patterns. Scout the opponent’s cooling habits. If they rush serving after long rallies, extend points early in games and then slow them with higher trajectories and depth. If they spend extra time toweling on return, use quick serve patterns to the body.
Use the rule’s structure
- If a cooling break is likely, choose whether to push for a fast finish to set two or conserve and surge after the pause.
- Against a front runner, saving energy and breaking in the first two games of set three can be higher percentage than chasing a low probability comeback late in set two.
- If a suspension is possible, monitor cloud cover and wind. As WBGT dips toward safe levels, be ready to restart sharp. Keep a mini warm up sequence ready during stoppages.
What juniors, parents, and coaches can do now
- Build acclimation into winter and spring blocks. Log simple markers like sleep quality and resting heart rate.
- Teach a two bottle system: one water, one electrolyte plus carbohydrate. Label them and set target volumes per set.
- Rehearse the 10 minute half time so the routine is automatic on tournament day.
- Align school, practice, and match schedules with expected conditions. If your region is cooler, simulate heat with indoor heaters or light overdressing for short blocks.
- Communicate medical red flags. Fever or viral illness reduces heat tolerance, so shorten or skip sessions.
For more match specific ideas tied to WBGT and momentum, see our tactical breakdown in ATP 2026 heat policy match tactics.
A final note on rules at the majors
Grand Slams set their own policies and some already use WBGT, while the Australian Open runs a different heat stress scale. Expect variation across the calendar, so build routines around WBGT principles, not just a single number. The 2026 ATP rule gives you a solid baseline for most of the year, and the habits you build will carry across tours and levels.
The smart next step
The 2026 heat policy is more than a safety net. It is a new metronome for training and match play. Use the four week acclimation block to raise your ceiling, personalize fluids and sodium with a simple sweat test, rehearse the 10 minute cooling break exactly as you will execute it, and tune your equipment for hot courts. Start now and script your own heat plan so that when WBGT hits 30.1 degrees and the break arrives, you are the player who walks back on court sharper, calmer, and ready to take the first two games of the third set.