Frost Dates for 55731 — Ely, Minnesota

Half of springs at Ely, MN see their last 32°F night by May 24; only one in ten is past it by May 10, and one in ten still has one after June 4. Planting tender crops after May 29 leaves a 30% risk of a frost on them, after May 31 20%, and after June 4 10%. The 11 days between the even-odds date and the one-in-ten date is the narrowest of the 142 Minnesota stations behind this site's ZIP pages.

In fall the first 32°F night comes by September 23 in half of years, as early as September 7 one year in ten, and holds off past October 7 one year in ten. A hard freeze of 28°F follows 11 days later, around October 4; in spring the one-in-ten date for 28°F is May 25, 10 days before the 32°F one. The freeze-free season lasts 121 days in a typical year, shorter than at 96% of the 142 Minnesota stations; it reaches 141 days one year in ten and falls short of 103 one year in ten. On average 200 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 June 3, and return around September 13. Severe cold of 16°F or below comes every winter, usually between November 6 and April 12.

July is the warmest month at Ely, MN, averaging 79°F by day and 53°F at night; January is the coldest at 15°F and -7°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 20% of years.

Warmth for growing adds up to 1,719 growing degree days a year (base 50°F), fewer than at 91% of the 142 Minnesota stations. 30% of them (516) have built up by the end of June, and July adds the most, 499. Precipitation totals 31.3 inches a year, most in September (4.8") and least in February (0.8"); May to September bring 64% of it.

The nearest other station, Babbitt, MN, 14 miles south of Ely, has a last frost 4 days later (May 28), a first frost 9 days earlier (September 14), a season 13 days shorter.

The first measurable snow (0.1 inch or more) in Ely usually arrives around October 19, and the last of the season around April 28. Those are the middle dates across the winters of 1991–2020 at Babbitt, MN, 14 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 26 days after the last snow.

ZIP 55731 is 3 miles from Ely, MN, which stands at 1,382 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 55731 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.