Weather & Climate
Frost-free season calculator.
Calculate the elapsed growing-season length from two observed or published frost dates.
Frost dates
Frost-free interval
Fill the form and press Calculate.
Choose the dates carefully
Use dates from the same frost definition and the same location. “Last frost” and “first frost” can mean different thresholds, such as 0°C / 32°F or a lighter freeze. The result is the elapsed number of calendar days between the two dates; it does not forecast frost or account for microclimates.
For official station normals, start with the climate service for your country. NOAA NCEI’s Climate Normals includes growing-season statistics for many U.S. stations. Other national meteorological services publish equivalent station or regional products.
Location matters
Garden, farm, and outdoor-work decisions should account for elevation, slope, urban heat, shelter, and the exact frost threshold relevant to the plant or task.