Frost Dates for 55952 — Lewiston, Minnesota

Half of springs at Rushford, MN see their last 32°F night by May 8; only one in ten is past it by April 25, and one in ten still has one after May 22. Planting tender crops after May 14 leaves a 30% risk of a frost on them, after May 17 20%, and after May 22 10%. The 14 days between the even-odds date and the one-in-ten date is narrower than at 37% of the 142 Minnesota stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 3 in half of years, as early as September 21 one year in ten, and holds off past October 16 one year in ten. A hard freeze of 28°F follows 9 days later, around October 12; in spring the one-in-ten date for 28°F is May 12, 10 days before the 32°F one. The freeze-free season lasts 147 days in a typical year, shorter than at 62% of the 142 Minnesota stations; it reaches 164 days one year in ten and falls short of 127 one year in ten. On average 167 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 10 days longer, to about May 18, and return around September 25. Severe cold of 16°F or below comes every winter, usually between November 12 and March 29.

July is the warmest month at Rushford, MN, averaging 82°F by day and 59°F at night; January is the coldest at 26°F and 5°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 76% of years.

Warmth for growing adds up to 2,448 growing degree days a year (base 50°F), more than at 51% of the 142 Minnesota stations. 33% of them (803) have built up by the end of June, and July adds the most, 643. Precipitation totals 37.1 inches a year, most in June (5.7") and least in January (1.1"); May to September bring 63% of it.

The nearest other station, Winona, MN, 12 miles northeast of Lewiston, has a last frost 17 days earlier (April 21), a first frost 16 days later (October 19), a season 33 days longer.

The first measurable snow (0.1 inch or more) in Lewiston usually arrives around November 16, and the last of the season around April 10. Those are the middle dates across the winters of 1991–2020 at Altura 5W, MN, 11.9 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 28 days after the last snow.

ZIP 55952 is 12 miles from Rushford, MN, which stands at 770 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 2 other ZIP codes share the station; its figures are presented in full for 55943 (Houston). The 2023 USDA Plant Hardiness Zone Map lists ZIP 55952 in zone 4b, the band where the coldest night of the year averaged -25 to -20°F (-31.7 to -28.9°C) over 1991–2020; a zone describes winter lows, not frost dates.