Frost Dates for 62301 — Quincy, Illinois

Half of springs at Quincy Dam 21, IL see their last 32°F night by April 8; only one in ten is past it by March 24, and one in ten still has one after April 23. Planting tender crops after April 15 leaves a 30% risk of a frost on them, after April 18 20%, and after April 23 10%. The 15 days between the even-odds date and the one-in-ten date is narrower than at 54% of the 158 Illinois stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 30 in half of years, as early as October 17 one year in ten, and holds off past November 10 one year in ten. A hard freeze of 28°F follows 9 days later, around November 8; in spring the one-in-ten date for 28°F is April 14, 9 days before the 32°F one. The freeze-free season lasts 204 days in a typical year, longer than at 94% of the 158 Illinois stations; it reaches 223 days one year in ten and falls short of 182 one year in ten. On average 112 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 11 days longer, to about April 19, and return around October 20. Severe cold of 16°F or below comes every winter, usually between December 6 and March 4.

July is the warmest month at Quincy Dam 21, IL, averaging 87°F by day and 68°F at night; January is the coldest at 35°F and 19°F. A freezing night is all but certain in every month from November to March (a 90% chance or more). From May to September the chance of a 32°F night stays under 10% each month. In spring, April still brings one in 76% of years.

Warmth for growing adds up to 3,861 growing degree days a year (base 50°F), more than at 77% of the 158 Illinois stations. 36% of them (1,387) have built up by the end of June, and July adds the most, 849. Precipitation totals 36.5 inches a year, most in May (4.8") and least in January (1.7"); May to September bring 53% of it.

The nearest other station, Quincy Regional Airport, IL, 10 miles east of Quincy and 286 feet higher, has a last frost 6 days later (April 14), a first frost 7 days earlier (October 23), a season 13 days shorter.

The first measurable snow (0.1 inch or more) in Quincy usually arrives around December 17, and the last of the season around February 19. Those are the middle dates across the winters of 1991–2020 at Quincy Dam 21, IL, 3.4 miles away: half of years saw snow earlier, half later. Snow fell in 96% of those winters. The last 32°F night of spring typically comes 48 days after the last snow.

ZIP 62301 is 3 miles from Quincy Dam 21, IL, which stands at 483 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 1 other ZIP code shares the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 62301 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.