Bowbells, ND 58721 Frost Dates
58721, near Bowbells, ND: the frost window
Typically, the last spring freeze lands around 05/20, roughly 265 days out. Fall's first freeze usually shows up around 09/19, roughly 121 days after the last spring frost.
Zone 4a (-30 to -25°F average annual minimum) comes from the USDA Plant Hardiness Zone Map; the frost dates above are the 1991-2020 normal at the nearest reporting NOAA station for Bowbells, not a forecast for this year.
Stretching the season past the first frost
Bowbells'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.
Why 05/20 isn't a guarantee
05/20 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 05/09 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 06/02 and only about 1 year in 10 sees frost after that.
Bowbells against the rest of the dataset
About 121 days separate Bowbells's last and first frost, putting it 39,048 of 40,283 ZIP codes nationally. Within ND, it ranks 383 of 405.
Learn more
Two guides worth reading on 58721: the frost range, on how to read the range around Bowbells's dates instead of trusting one, and local microclimates, on what one yard in Bowbells can differ from the 58721 normal.