Frost Dates for 52738 — Columbus Junction, Iowa

Half of springs at Columbus Junction, IA 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 11. Planting tender crops after May 2 leaves a 30% risk of a frost on them, after May 5 20%, and after May 11 10%. The 15 days between the even-odds date and the one-in-ten date is wider than at 82% of the 132 Iowa stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 10 in half of years, as early as September 23 one year in ten, and holds off past October 22 one year in ten. A hard freeze of 28°F follows 11 days later, around October 21; in spring the one-in-ten date for 28°F is April 30, 11 days before the 32°F one. The freeze-free season lasts 167 days in a typical year, longer than at 60% of the 132 Iowa stations; it reaches 186 days one year in ten and falls short of 146 one year in ten. On average 134 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 1. Severe cold of 16°F or below comes every winter, usually between November 17 and March 18.

July is the warmest month at Columbus Junction, IA, averaging 84°F by day and 63°F at night; January is the coldest at 30°F and 11°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 36% of years.

Warmth for growing adds up to 3,051 growing degree days a year (base 50°F), more than at 55% of the 132 Iowa stations. 35% of them (1,066) have built up by the end of June, and July adds the most, 725. Precipitation totals 38.8 inches a year, most in May (5.4") and least in January (1.2"); May to September bring 58% of it.

The nearest other station, New Boston Dam 17, IL, 17 miles east of Columbus Junction, has a last frost 12 days earlier (April 14), a first frost 14 days later (October 24), a season 23 days longer.

The first measurable snow (0.1 inch or more) in Columbus Junction usually arrives around December 1, and the last of the season around March 16. Those are the middle dates across the winters of 1991–2020 at Columbus Junction, IA, 0.9 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 41 days after the last snow.

ZIP 52738 is under a mile from Columbus Junction, IA, which stands at 590 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 52738 in zone 5b, the band where the coldest night of the year averaged -15 to -10°F (-26.1 to -23.3°C) over 1991–2020; a zone describes winter lows, not frost dates.