Frost Dates for 54452 — Merrill, Wisconsin

Half of springs at Merrill, WI see their last 32°F night by May 11; only one in ten is past it by April 29, and one in ten still has one after May 27. Planting tender crops after May 18 leaves a 30% risk of a frost on them, after May 21 20%, and after May 27 10%. The 16 days between the even-odds date and the one-in-ten date is wider than at 70% of the 182 Wisconsin stations behind this site's ZIP pages.

In fall the first 32°F night comes by September 30 in half of years, as early as September 17 one year in ten, and holds off past October 12 one year in ten. A hard freeze of 28°F follows 10 days later, around October 10; in spring the one-in-ten date for 28°F is May 16, 11 days before the 32°F one. The freeze-free season lasts 139 days in a typical year, shorter than at 86% of the 182 Wisconsin stations; it reaches 157 days one year in ten and falls short of 120 one year in ten. On average 182 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 13 days longer, to about May 24, and return around September 20. Severe cold of 16°F or below comes every winter, usually between November 13 and April 3.

July is the warmest month at Merrill, WI, averaging 80°F by day and 57°F at night; January is the coldest at 22°F and 3°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 85% of years.

Warmth for growing adds up to 2,079 growing degree days a year (base 50°F), fewer than at 83% of the 182 Wisconsin stations. 32% of them (674) have built up by the end of June, and July adds the most, 578. Precipitation totals 33.9 inches a year, most in June (4.6") and least in February (1.1"); May to September bring 59% of it.

The nearest other station, Wausau Dwtn Airport, WI, 18 miles south of Merrill, has a last frost 5 days earlier (May 6), a first frost 4 days later (October 4), a season 11 days longer.

The first measurable snow (0.1 inch or more) in Merrill usually arrives around November 5, and the last of the season around April 13. Those are the middle dates across the winters of 1991–2020 at Merrill, WI, 2.1 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 54452 is 2 miles from Merrill, WI, which stands at 1,250 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 54452 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.