Berthold, ND 58718 Frost Dates
58718, near Berthold, ND: the frost window
The last spring frost here typically falls around 05/11, about 256 days from today. Fall's first freeze usually shows up around 09/29, roughly 138 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 Berthold, not a forecast for this year.
Stretching the season past the first frost
Berthold'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.
The actual range around Berthold's last frost
05/11 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/28 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/29 and only about 1 year in 10 sees frost after that.
Berthold against the rest of the dataset
Berthold's growing season runs about 138 days, ranking 37,447 of 40,283 US ZIP codes measured here, longest to shortest. Within ND, it ranks 188 of 405.
Learn more
Two guides worth reading on 58718: zone vs. frost date, on why Zone 4a and Berthold's frost date answer different questions, and the frost range, on how to read the range around Berthold's dates instead of trusting one.