Frost Dates for 62959 — Marion, Illinois

Half of springs at Carbondale Sewage Plt, IL see their last 32°F night by April 9; only one in ten is past it by March 25, 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 10 one year in ten, and holds off past November 2 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 214 days one year in ten and falls short of 175 one year in ten. On average 103 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 13 days longer, to about April 22, and return around October 13. Severe cold of 16°F or below comes every winter, usually between December 10 and February 25.

July is the warmest month at Carbondale Sewage Plt, IL, averaging 88°F by day and 68°F at night; January is the coldest at 41°F and 23°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 72% of years.

Warmth for growing adds up to 4,111 growing degree days a year (base 50°F), more than at 87% of the 158 Illinois stations. 38% of them (1,550) have built up by the end of June, and July adds the most, 863. Precipitation totals 49.0 inches a year, most in April (5.6") and least in February (3.1"); May to September bring 42% of it.

The nearest other station, Carbondale Southern Il Airport, IL, 18 miles west of Marion, has the same 50% last-frost date, the same first-frost date.

The first measurable snow (0.1 inch or more) in Marion usually arrives around December 27, and the last of the season around February 18. Those are the middle dates across the winters of 1991–2020 at Carbondale Sewage Plt, IL, 12.9 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 50 days after the last snow.

ZIP 62959 is 13 miles from Carbondale Sewage Plt, IL, which stands at 390 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 5 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 62959 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.