Frost Dates for 55616 — Two Harbors, Minnesota

Half of springs at Two Harbors, MN see their last 32°F night by May 12; only one in ten is past it by April 30, and one in ten still has one after May 30. Planting tender crops after May 19 leaves a 30% risk of a frost on them, after May 24 20%, and after May 30 10%. The 18 days between the even-odds date and the one-in-ten date is wider than at 92% of the 142 Minnesota stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 6 in half of years, as early as September 19 one year in ten, and holds off past October 21 one year in ten. A hard freeze of 28°F follows 14 days later, around October 20; in spring the one-in-ten date for 28°F is May 11, 19 days before the 32°F one. The freeze-free season lasts 145 days in a typical year, shorter than at 65% of the 142 Minnesota stations; it reaches 167 days one year in ten and falls short of 122 one year in ten. On average 164 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 16 days longer, to about May 28, and return around September 27. Severe cold of 16°F or below comes every winter, usually between November 16 and March 30.

August is the warmest month at Two Harbors, MN, averaging 75°F by day and 56°F at night; January is the coldest at 24°F and 7°F. A freezing night is all but certain in every month from October to April (a 90% chance or more). From June to August the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 86% of years.

Warmth for growing adds up to 1,492 growing degree days a year (base 50°F), fewer than at 99% of the 142 Minnesota stations. 18% of them (267) have built up by the end of June, and August adds the most, 473. Precipitation totals 31.8 inches a year, most in June (4.2") and least in January (1.0"); May to September bring 58% of it.

The nearest other station, Island Lake 4E, MN, 19 miles west of Two Harbors and 785 feet higher, has a last frost 9 days later (May 21), a first frost 9 days earlier (September 27), a season 16 days shorter.

The first measurable snow (0.1 inch or more) in Two Harbors usually arrives around November 21, and the last of the season around April 12. Those are the middle dates across the winters of 1991–2020 at Two Harbors, 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 30 days after the last snow.

ZIP 55616 is 4 miles from Two Harbors, MN, which stands at 625 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 55616 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.