Frost Dates for 56630 — Blackduck, Minnesota

Half of springs at Blackduck, MN see their last 32°F night by May 24; only one in ten is past it by May 9, and one in ten still has one after June 6. Planting tender crops after May 29 leaves a 30% risk of a frost on them, after June 1 20%, and after June 6 10%. The 13 days between the even-odds date and the one-in-ten date is narrower than at 61% of the 142 Minnesota stations behind this site's ZIP pages.

In fall the first 32°F night comes by September 17 in half of years, as early as September 1 one year in ten, and holds off past October 1 one year in ten. A hard freeze of 28°F follows 11 days later, around September 28; in spring the one-in-ten date for 28°F is May 27, 10 days before the 32°F one. The freeze-free season lasts 115 days in a typical year, shorter than at 98% of the 142 Minnesota stations; it reaches 136 days one year in ten and falls short of 91 one year in ten. On average 196 nights a year drop to 32°F or below. Nights of 36°F, when frost can still settle on leaves in low, open spots, continue 11 days longer, to about June 4, and return around September 6. Severe cold of 16°F or below comes every winter, usually between November 2 and April 13.

July is the warmest month at Blackduck, MN, averaging 78°F by day and 54°F at night; January is the coldest at 18°F and -9°F. A freezing night is all but certain in every month from October to May (a 90% chance or more). From July to August the chance of a 32°F night stays under 10% each month. In spring, June still brings one in 22% of years.

Warmth for growing adds up to 1,635 growing degree days a year (base 50°F), fewer than at 95% of the 142 Minnesota stations. 30% of them (493) have built up by the end of June, and July adds the most, 493.

The nearest other station, Cass Lake, MN, 24 miles south of Blackduck, has a last frost 7 days earlier (May 17), a first frost 9 days later (September 26), a season 16 days longer.

The first measurable snow (0.1 inch or more) in Blackduck usually arrives around October 29, and the last of the season around April 19. Those are the middle dates across the winters of 1991–2020 at Blackduck, MN, 3.6 miles away: half of years saw snow earlier, half later. Every one of those winters saw snow. The last 32°F night of spring typically comes 35 days after the last snow.

ZIP 56630 is 4 miles from Blackduck, MN, which stands at 1,340 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 56630 in zone 3b, the band where the coldest night of the year averaged -35 to -30°F (-37.2 to -34.4°C) over 1991–2020; a zone describes winter lows, not frost dates.