Frost Dates for 62903 — Carbondale, Illinois

Half of springs at Carbondale Southern Il Airport, IL see their last 32°F night by April 9; only one in ten is past it by March 24, and one in ten still has one after April 25. Planting tender crops after April 16 leaves a 30% risk of a frost on them, after April 20 20%, and after April 25 10%. The 16 days between the even-odds date and the one-in-ten date is narrower than at 22% of the 158 Illinois stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 22 in half of years, as early as October 8 one year in ten, and holds off past November 1 one year in ten. A hard freeze of 28°F follows 10 days later, around November 1; in spring the one-in-ten date for 28°F is April 14, 11 days before the 32°F one. The freeze-free season lasts 195 days in a typical year, longer than at 78% of the 158 Illinois stations; it reaches 213 days one year in ten and falls short of 175 one year in ten. On average 95 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 April 21, and return around October 12. Severe cold of 16°F or below comes every winter, usually between December 8 and February 22.

July is the warmest month at Carbondale Southern Il Airport, IL, averaging 88°F by day and 68°F at night; January is the coldest at 42°F and 25°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 77% of years.

Warmth for growing adds up to 4,161 growing degree days a year (base 50°F), more than at 90% of the 158 Illinois stations. 38% of them (1,600) have built up by the end of June, and July adds the most, 866. Precipitation totals 44.0 inches a year, most in April (5.3") and least in February (2.6"); May to September bring 43% of it.

The nearest other station, Carbondale Sewage Plt, IL, 14 miles east of Carbondale, has the same 50% last-frost date, the same first-frost date.

The first measurable snow (0.1 inch or more) in Carbondale usually arrives around January 6, and the last of the season around February 16. Those are the middle dates across the winters of 1991–2020 at Murphysboro 2 SW, IL, 2.7 miles away: half of years saw snow earlier, half later. Snow fell in 87% of those winters. The last 32°F night of spring typically comes 52 days after the last snow.

ZIP 62903 is 9 miles from Carbondale Southern Il Airport, IL, which stands at 406 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 3 other ZIP codes share the station; its figures are presented in full for 62966 (Murphysboro). The 2023 USDA Plant Hardiness Zone Map lists ZIP 62903 in zone 7a, the band where the coldest night of the year averaged 0 to 5°F (-17.8 to -15.0°C) over 1991–2020; a zone describes winter lows, not frost dates.