Frost Risk Calculator
Gauge tonight's frost risk from the forecast minimum temperature, dew point and sky/wind conditions.
Radiation frost forms on clear, calm nights when heat radiates to the sky; cloud or wind greatly reduce it. A low dew point lets temperature keep falling, while a dew point near the forecast min limits the drop. Treat a forecast min at or below 2°C on a clear calm night with a freezing dew point as high risk.
Indicative planning figures based on published research averages. Local soil tests, varieties and weather change actual requirements — confirm with your agronomist or extension officer.
Orchardists and growers use the free Frost Risk Calculator for an accurate answer in seconds — no formulas to remember, works offline in the orchard.
About Frost Risk Calculator
Deciding whether to fire up frost protection tonight is a costly call either way. This tool weighs the three things that drive radiation frost — the forecast minimum temperature, the dew point (a low one lets temperature keep plunging), and whether the night is clear and calm (cloud and wind suppress frost). It returns a simple risk level and advice so you can protect blossom or young fruit when it matters and save effort when it doesn't.
How to use Frost Risk Calculator
- 1Enter your values into the inputs.
- 2Read the headline result and the supporting breakdown.
- 3Apply the guidance in the note to your orchard decisions.
Why use Frost Risk Calculator?
- ✓Uses the standard, citable formula
- ✓Clear inputs with sensible defaults
- ✓Instant result with the working shown
- ✓Free, fully in-browser and private
Frequently asked questions
Will it frost tonight?+
Frost is likely on a clear, calm night when the forecast minimum is near or below 0°C and the dew point is also at or below freezing. Cloud cover or wind sharply reduce radiation-frost risk. This tool combines these factors into a risk level.
What's the difference between dew point and frost?+
Dew point is the saturation temperature. If it's above 0°C, condensation forms as dew; if at or below 0°C, it forms as frost. A low dew point also means the air can cool further before condensing, allowing a harder freeze.
Is this tool free and private?+
Yes — free, no sign-up, and all calculation runs in your browser, so it works offline in the orchard and your data never leaves the device.
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