Frost Dates for 52211 — Brooklyn, Iowa

Half of springs at Belle Plaine, IA see their last 32°F night by April 28; only one in ten is past it by April 14, and one in ten still has one after May 11. Planting tender crops after May 3 leaves a 30% risk of a frost on them, after May 7 20%, and after May 11 10%. The 13 days between the even-odds date and the one-in-ten date is narrower than at 42% 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 26 one year in ten, and holds off past October 23 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 May 2, 9 days before the 32°F one. The freeze-free season lasts 165 days in a typical year, shorter than at 45% of the 132 Iowa stations; it reaches 185 days one year in ten and falls short of 145 one year in ten. On average 153 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 8 days longer, to about May 6, and return around October 1. Severe cold of 16°F or below comes every winter, usually between November 17 and March 16.

July is the warmest month at Belle Plaine, IA, averaging 84°F by day and 63°F at night; January is the coldest at 28°F and 10°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 39% of years.

Warmth for growing adds up to 2,989 growing degree days a year (base 50°F), fewer than at 52% of the 132 Iowa stations. 35% of them (1,048) have built up by the end of June, and July adds the most, 721. Precipitation totals 36.1 inches a year, most in June (5.2") and least in January (1.1"); May to September bring 59% of it.

The nearest other station, Grinnell 3 SW, IA, 16 miles west of Brooklyn, has a last frost 5 days later (May 3), a first frost 4 days earlier (October 6), a season 10 days shorter.

The first measurable snow (0.1 inch or more) in Brooklyn usually arrives around November 26, and the last of the season around March 21. Those are the middle dates across the winters of 1991–2020 at Brooklyn, IA, 1.1 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 38 days after the last snow.

ZIP 52211 is 13 miles from Belle Plaine, IA, which stands at 810 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 1 other ZIP code shares the station; its figures are presented in full for 52208 (Belle Plaine). The 2023 USDA Plant Hardiness Zone Map lists ZIP 52211 in zone 5a, the band where the coldest night of the year averaged -20 to -15°F (-28.9 to -26.1°C) over 1991–2020; a zone describes winter lows, not frost dates.