Estimate frost risk from forecast low temperature, dew point, humidity, wind speed, cloud cover, plant exposure, and terrain. This calculator helps gardeners, growers, homeowners, and outdoor planners check whether frost is possible overnight.
Temperature:
The forecast low temperature is the main driver. Temperatures near or below freezing increase frost and freeze potential.
Dew point and humidity:
Moist air near freezing can support frost formation on exposed surfaces.
Wind and clouds:
Clear skies allow heat to escape overnight. Light wind can allow cold air to settle, while stronger wind can reduce frost formation.
Terrain and exposure:
Low spots, exposed plants, containers, and tender plants can have higher frost risk than sheltered areas.
A frost risk calculator is useful for gardeners, farmers, landscapers, greenhouse growers, orchard planning, container plants, spring planting, fall cleanup, and deciding whether plants may need covering overnight.
This is a rough planning estimate. Actual frost depends on local microclimates, soil warmth, elevation, cloud timing, wind shifts, plant height, surface temperature, and official weather conditions.
Your result shows an estimated frost risk score from 0 to 100. Higher scores mean conditions are more favorable for frost or freeze damage. Lower scores mean frost is less likely based on the entered weather and site conditions.
Yes. Surface temperatures on plants, roofs, cars, or grass can fall below freezing even when the measured air temperature is a few degrees above 32°F.
Frost is more likely during clear, calm, humid nights when temperatures are near freezing and surfaces can cool quickly.
Frost refers to ice crystals forming on surfaces. A freeze means air temperatures fall to 32°F or lower, which can damage sensitive plants even without visible frost.
If tender plants are exposed and the risk is moderate or higher, covering them or moving containers to shelter can help reduce damage.