Petersburg, ND 58272 Frost Dates
Petersburg, ND: when does the frost end?
Around 05/11 is the usual last spring frost, about 256 days away. Fall's first freeze usually shows up around 09/28, roughly 138 days after the last spring frost.
Petersburg sits in USDA Zone 4a (-30 to -25°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
With roughly 4 weeks until Petersburg's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
Why 05/11 isn't a guarantee
05/11 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/29 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/25 and only about 1 year in 10 sees frost after that.
Petersburg against the rest of the dataset
About 138 days separate Petersburg's last and first frost, putting it 37,468 of 40,283 ZIP codes nationally. Within ND, it ranks 199 of 405.
Learn more
Before leaning on 58272's figures: zone vs. frost date explains why Zone 4a and Petersburg's frost date answer different questions, while the frost range explains how to read the range around Petersburg's dates instead of trusting one.