Frost Dates for 52001 — Dubuque, Iowa

Half of springs at Dubuque L&D 11, IA see their last 32°F night by April 19; only one in ten is past it by April 4, and one in ten still has one after May 4. Planting tender crops after April 25 leaves a 30% risk of a frost on them, after April 30 20%, and after May 4 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 21 in half of years, as early as October 7 one year in ten, and holds off past November 2 one year in ten. A hard freeze of 28°F follows 11 days later, around November 1; in spring the one-in-ten date for 28°F is April 22, 12 days before the 32°F one. The freeze-free season lasts 184 days in a typical year, longer than at 89% of the 132 Iowa stations; it reaches 203 days one year in ten and falls short of 164 one year in ten. On average 133 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 12 days longer, to about May 1, and return around October 12. Severe cold of 16°F or below comes every winter, usually between November 28 and March 14.

July is the warmest month at Dubuque L&D 11, IA, averaging 85°F by day and 64°F at night; January is the coldest at 28°F and 10°F. A freezing night is all but certain in every month from November to April (a 90% chance or more). From June to September the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 18% of years.

Warmth for growing adds up to 3,078 growing degree days a year (base 50°F), more than at 61% of the 132 Iowa stations. 34% of them (1,040) have built up by the end of June, and July adds the most, 755. Precipitation totals 38.8 inches a year, most in June (5.6") and least in January (1.3"); May to September bring 59% of it.

The nearest other station, Dubuque Regional Airport, IA, 8 miles south of Dubuque and 436 feet higher, has a last frost 9 days later (April 28), a first frost 10 days earlier (October 11), a season 19 days shorter.

The first measurable snow (0.1 inch or more) in Dubuque usually arrives around December 4, and the last of the season around March 20. Those are the middle dates across the winters of 1991–2020 at Dubuque L&D 11, IA, 2.4 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 30 days after the last snow.

ZIP 52001 is 2 miles from Dubuque L&D 11, IA, which stands at 620 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 3 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 52001 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.