Riverdale, ND 58565 Frost Dates
58565, near Riverdale, ND: the frost window
The last spring frost here typically falls around 05/12, about 257 days from today. Fall's first freeze usually shows up around 10/03, roughly 143 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Riverdale in Zone 4a (-30 to -25°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
Stretching the season past the first frost
Riverdale's growing season runs out in roughly 5 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
Why 05/12 isn't a guarantee
05/12 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/30 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/27 and only about 1 year in 10 sees frost after that.
Riverdale against the rest of the dataset
About 143 days separate Riverdale's last and first frost, putting it 36,640 of 40,283 ZIP codes nationally. Within ND, it ranks 96 of 405.
Learn more
Two guides worth reading on 58565: zone vs. frost date, on why Zone 4a and Riverdale's frost date answer different questions, and the frost range, on how to read the range around Riverdale's dates instead of trusting one.