Castle Valley, UT 81522 Frost Dates
81522, near Castle Valley, UT: the frost window
Around 04/20 is the usual last spring frost, about 235 days away. Fall's first freeze usually shows up around 10/21, roughly 182 days after the last spring frost.
Castle Valley sits in USDA Zone 6b (-5 to 0°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
Castle Valley's growing season runs out in roughly 8 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 Castle Valley's last frost
04/20 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/01 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/05 and only about 1 year in 10 sees frost after that.
Castle Valley against the rest of the dataset
About 182 days separate Castle Valley's last and first frost, putting it 24,300 of 40,283 ZIP codes nationally. Within UT, it ranks 97 of 344.
Learn more
Two guides worth reading on 81522: local microclimates, on what one yard in Castle Valley can differ from the 81522 normal, and zone vs. frost date, on why Zone 6b and Castle Valley's frost date answer different questions.