Castleford, ID 89826 Frost Dates
89826, near Castleford, ID: the frost window
Typically, the last spring freeze lands around 06/09, roughly 285 days out. Fall's first freeze usually shows up around 09/16, roughly 96 days after the last spring frost.
Castleford sits in USDA Zone 6a (-10 to -5°F average annual minimum). The dates above are NOAA's 1991-2020 normal at the nearest reporting station, a 30-year average, not a forecast.
Stretching the season past the first frost
Castleford's growing season runs out in roughly 3 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
The actual range around Castleford's last frost
06/09 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 05/24 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 06/26 and only about 1 year in 10 sees frost after that.
Castleford against the rest of the dataset
About 96 days separate Castleford's last and first frost, putting it 39,807 of 40,283 ZIP codes nationally. Within ID, it ranks 258 of 320.
Learn more
Two guides worth reading on 89826: the frost range, on how to read the range around Castleford's dates instead of trusting one, and local microclimates, on what one yard in Castleford can differ from the 89826 normal.