Frost Watch

Now powered by Apple Weather. A clear 0–10 frost risk score for tonight and the week ahead, with notifications. Built for gardeners who can't afford a surprise freeze.

Your weather app says 34°F. But at ground level - where your plants actually live - it's 26°F. That difference is the reason you keep losing plants to "surprise" frosts.

Frost Watch uses atmospheric science to predict what's really happening at ground level. Instead of relying on a simple temperature threshold, it calculates frost risk using dew point, cloud cover, wind speed, humidity, and radiative cooling physics - the same factors professional meteorologists use.

HOW IT WORKS

Frost forms through radiative cooling: on clear, calm nights, the ground loses heat to the sky and can drop 6-8°F below the forecast air temperature. Frost Watch models this process using peer-reviewed research from the FAO, NOAA, and published atmospheric science, then distills it into a simple 0-10 risk score.

Every evening, you get a score, an explanation of why, and specific advice on what to do.

FEATURES

• Ground Temperature Estimation See both the forecast air temperature and the estimated ground-level temperature side by side. Understand why frost can form even when the forecast says 34°F.

• 0-10 Risk Score A single number that accounts for cloud cover, wind speed, dew point, humidity, and recent precipitation. Each factor's impact is shown so you understand exactly why tonight is risky - or safe.

• 7-Day Frost Forecast Plan your week with daily overnight frost risk scores. Tap any day for hourly breakdowns and detailed weather factors.

• 67 Plant-Specific Alerts + Pipes Add your plants from a curated database of vegetables, fruits, flowers, and tropicals. Each has scientifically researched damage and kill temperatures. When ground temps approach your plants' thresholds, you'll see exactly which ones need protection and what to do.

• Evening Notifications Get alerts at a time you choose (default 7 PM) so you have time to cover plants or bring containers inside before nightfall. Set your risk threshold, lookahead window (up to 7 days), and quiet weekends. Notifications are scheduled in advance and fire even if you don't open the app.

• Daytime Frost Detection Most apps only check overnight lows. Frost Watch also scans for rare daytime freezes - devastating for spring blooms - and alerts you the evening before.

• Home Screen Widgets Small and medium widgets show tonight's risk score and upcoming forecast at a glance. No need to open the app to know if tonight matters.

• Works Everywhere Enter any location worldwide. Uses Open-Meteo weather data with automatic timezone detection.

BUILT FOR GARDENERS, BACKED BY SCIENCE

Frost Watch was built because generic weather apps don't tell you what you actually need to know: will frost form tonight, and should I do something about it? The answer depends on more than temperature. It depends on whether the sky is clear enough for radiative cooling, whether wind will mix the air and prevent inversions, whether the dew point is close enough to buffer heat loss, and whether recent rain changed the soil's thermal properties.

This app does that math for you and gives you a clear answer every evening.

°F or °C. 12h or 24h. Your units, your schedule, your plants.

No account. No subscription. No tracking. Ever. All your data stays on your device. Just open the app and protect your garden.