Seneca, IL 61360 Frost Dates
When can you plant in Seneca, IL?
Around 04/27 is the usual last spring frost, about 242 days away. The first fall frost typically arrives around 10/17, about 171 frost-free days later.
The USDA Plant Hardiness Zone Map puts Seneca in Zone 5b (-15 to -10°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
What to do before the first frost
About 7 weeks of growing season left in Seneca before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
Why 04/27 isn't a guarantee
04/27 is the middle of 30 years of NOAA records, not a promise. Plant by 04/12 and you're betting against frost in roughly 9 years out of 10. 05/13 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Seneca compares
At roughly 171 frost-free days, Seneca places 28,677 of 40,283 ZIP codes in this dataset. Within IL, it ranks 1,375 of 1,548.
Learn more
the frost range covers how to read the range around Seneca's dates instead of trusting one. local microclimates covers what one yard in Seneca can differ from the 61360 normal.