CoolSplash: Watering Cooldown

Thinking of watering your yard or driveway to beat the heat? CoolSplash tells you — before you pick up the hose — how much cooler it will actually get, using real physics, not wishful thinking.

Enter nothing: CoolSplash reads the live temperature, humidity, wind and sunshine at your location. Pick your ground — asphalt, concrete, soil, grass or gravel — and see a clear before/after comparison of three numbers: the ground under your feet, the radiant heat it throws back at you, and the air itself.

The honest answer matters most on humid days: when the air is already saturated, watering barely works, and CoolSplash says so plainly with a 5-star effectiveness rating. On dry days you'll see exactly how far the pavement can drop.

The wet-bulb limit is computed with a peer-reviewed formula (Stull 2011), and the real-world ranges are calibrated against published field measurements of uchimizu — Japan's centuries-old street sprinkling tradition. Estimates are shown as ranges, as a guide.

One-time purchase, no subscription. All calculations run on your device — no data collection, no account, no ads. Works offline once weather data is fetched.