Petersburg, IL 62659 Frost Dates
When can you plant in Petersburg, IL?
Around 04/13 is the usual last spring frost, about 228 days away. The first fall frost typically arrives around 10/21, about 189 frost-free days later.
Petersburg sits in USDA Zone 6a (-10 to -5°F average annual minimum). The dates above are NOAA's 1991-2020 normal at the nearest reporting station, a 30-year average, not a forecast.
What to do before the first frost
About 8 weeks of growing season left in Petersburg before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
Why 04/13 isn't a guarantee
04/13 is the middle of 30 years of NOAA records, not a promise. Plant by 03/31 and you're betting against frost in roughly 9 years out of 10. 04/28 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Petersburg compares
Petersburg's growing season runs about 189 days, ranking 21,605 of 40,283 US ZIP codes measured here, longest to shortest. Within IL, it ranks 608 of 1,548.
Learn more
local microclimates covers what one yard in Petersburg can differ from the 62659 normal. zone vs. frost date covers why Zone 6a and Petersburg's frost date answer different questions.