On clear, calm nights the ground is 2–4° colder than the air temperature weather apps show. Frost Tonight estimates the temperature at your plants and sends one message the evening before, only when one of them is at risk.
Air temperature is measured 2 m above the ground. On a clear, still night the ground radiates its heat away and gets several degrees colder. That is where frost hits first, and why a “4°” forecast still kills dahlias, tomatoes and geraniums.
Garden, allotment or balcony, up to three. Four quick questions: pots or beds, open or sheltered, low-lying or sloped, town or countryside.
Choose from 50+ common garden and balcony plants, each with its own frost threshold. Don’t know the name? Pick a type instead.
Every evening we combine the minimum temperature, cloud cover and wind into an estimate for your plants, and warn you only if one of them is at risk.
The temperature at your plants, the forecast next to it, and what to do: bring indoors or cover with fleece.
So you can plan when to move the pots and when to relax.
One notification the evening before, between 16:00 and 20:00. Never a message when all is well.
Citrus, dahlia, tomato, olive, geranium, and the winter plants too: heather, skimmia, conifers in pots, bulbs, winter pansies.
Shows your frost risk, even when you haven’t opened the app for days.
Forecasts for any location in Europe, calculated for a point within about 1 km of your garden.
Every garden is different. A hollow on the edge of town freezes long before a sheltered city balcony. Frost Tonight starts from your garden profile and keeps learning from you.
You hear from us only when a plant is at risk. No daily forecasts, no badges, no noise.
No name, no e-mail, no ads. Your exact location never leaves your phone; our server sees an area of about 1 km.
A physical model with cloud cover, wind and dew point, validated against ground-temperature observations and tuned by you.
Grass-temperature readings from the Danish Meteorological Institute (Karup, Roskilde, Kastrup and Bornholm), October 2025 to May 2026, calculated from the measured weather. Forecasts add their own uncertainty, which is why the app also learns from your answers.
then £9.99 / $9.99 / €9.99 a year. One price, every plant, every spot.
Coming soon to the App StoreYearly subscription through the App Store. Cancel any time in your Apple ID settings; nothing is charged during the trial.
Weather apps show the air temperature 2 m above ground. On clear, calm nights the ground, where your plants are, is typically 2–4° colder. We estimate that from the forecast’s minimum temperature, cloud cover and wind, tuned to your garden.
Yes. Forecasts come from Open-Meteo and national weather services and cover all of Europe. The app is in English, Danish, Norwegian, Swedish and German.
Answer “Yes, frost” in the app the next morning. That recalibrates the estimate for your spot. Also check that notifications are allowed for Frost Tonight.
Not yet, but it’s coming later.