90°F is the practical not-playable threshold for most recreational tennis players. Above this temperature, the combination of physical exertion and ambient heat creates real heat stress risk. Playable marks any morning above 90°F feels-like as not playable.
90
°F
Playable marks sessions not playable when the feels-like temperature exceeds 90°F during the 7–9 AM window.
Tennis is a high-exertion sport: a 90-minute recreational match can burn 600 or more calories. Add an ambient temperature of 90°F and your body's cooling system — sweating — starts losing the battle. Core temperature rises, reaction time slows, and the risk of heat exhaustion climbs meaningfully. The ATP tour suspends play above 104°F wet-bulb temperature; for recreational players without training staff and medical support, 90°F is a prudent working limit.
Dry 90°F feels very different from humid 90°F. Humidity inhibits sweat evaporation — your body's primary cooling mechanism. At 90°F with 80% humidity, the heat index can exceed 100°F. Playable evaluates feels-like temperature rather than raw temperature specifically to capture this effect. A humid 87°F morning can be more stressful than a dry 91°F morning.
In most hot-weather markets, the 7 AM temperature is 15–20°F lower than the afternoon peak. A day forecast at 100°F in Phoenix or Miami will typically be 80–84°F at 7 AM — well inside the playable range. The 7–9 AM window exists specifically to capture this gap. By 10 AM, conditions in many southern markets are already at or above threshold.
Even within the playable range, heat demands adjustment. Hydrate before you play, not just during. Take longer changeovers. Wear UV-protective, light-colored clothing. If you feel dizzy, nauseous, or stop sweating in heat, stop immediately — these are warning signs of heat exhaustion that require rest and cooling, not a short break before continuing.
Humidity
High humidity suppresses sweat evaporation and drives the heat index well above air temperature. Playable uses feels-like temperature to account for this.
Court surface
Dark asphalt hard courts can be 15–20°F hotter at court level than ambient air. Clay and lighter surfaces absorb less radiant heat.
Wind
Even light wind provides meaningful evaporative cooling. A 5 mph breeze at 89°F is meaningfully more comfortable than 89°F with no wind — though it won't override a heat index above threshold.
Time of day
Temperature rises quickly after sunrise. The 7 AM hour is the coolest playable window in most markets. By 9 AM, temperatures are already 3–5°F higher in warm conditions.
How Playable handles this
Playable uses feels-like temperature for its threshold evaluation, not raw air temperature — directly accounting for humidity's effect on heat stress. A 87°F morning with high humidity that feels like 96°F would be flagged not playable, even though the raw temperature reads below 90°F.
Playable gives you a 7-day playability forecast for your specific court. Free, no account needed.
Check This Week's Conditions →