Frost Dates for 63556 — Milan, Missouri

Half of springs at Green City 5N, MO see their last 32°F night by April 26; only one in ten is past it by April 11, and one in ten still has one after May 12. Planting tender crops after May 2 leaves a 30% risk of a frost on them, after May 5 20%, and after May 12 10%. The 16 days between the even-odds date and the one-in-ten date is narrower than at 35% of the 158 Missouri stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 14 in half of years, as early as September 30 one year in ten, and holds off past October 27 one year in ten. A hard freeze of 28°F follows 10 days later, around October 24; in spring the one-in-ten date for 28°F is April 30, 12 days before the 32°F one. The freeze-free season lasts 169 days in a typical year, shorter than at 98% of the 158 Missouri stations; it reaches 187 days one year in ten and falls short of 149 one year in ten. On average 139 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 9 days longer, to about May 5, and return around October 3. Severe cold of 16°F or below comes every winter, usually between November 20 and March 15.

July is the warmest month at Green City 5N, MO, averaging 85°F by day and 63°F at night; January is the coldest at 32°F and 13°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 35% of years.

Warmth for growing adds up to 3,140 growing degree days a year (base 50°F), the fewest of the 158 Missouri stations. 35% of them (1,096) have built up by the end of June, and July adds the most, 745. Precipitation totals 40.9 inches a year, most in May (5.6") and least in January (1.3"); May to September bring 60% of it.

The nearest other station, Unionville, MO, 21 miles north of Milan, has a last frost 9 days earlier (April 17), a first frost 8 days later (October 22), a season 17 days longer.

The first measurable snow (0.1 inch or more) in Milan usually arrives around December 5, and the last of the season around March 16. Those are the middle dates across the winters of 1991–2020 at Milan, MO, 2.6 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 41 days after the last snow.

ZIP 63556 is 15 miles from Green City 5N, MO, which stands at 1,035 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 63556 in zone 6a, the band where the coldest night of the year averaged -10 to -5°F (-23.3 to -20.6°C) over 1991–2020; a zone describes winter lows, not frost dates.