Saybrook, IL 61770 Frost Dates
When can you plant in Saybrook, IL?
The last spring frost here typically falls around 04/21, about 236 days from today. The first fall frost typically arrives around 10/17, about 178 frost-free days later.
Zone 6a (-10 to -5°F average annual minimum) comes from the USDA Plant Hardiness Zone Map; the frost dates above are the 1991-2020 normal at the nearest reporting NOAA station for Saybrook, not a forecast for this year.
What to do before the first frost
About 7 weeks of growing season left in Saybrook before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
Why 04/21 isn't a guarantee
04/21 is the middle of 30 years of NOAA records, not a promise. Plant by 04/10 and you're betting against frost in roughly 9 years out of 10. 05/05 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Saybrook compares
At roughly 178 frost-free days, Saybrook places 25,859 of 40,283 ZIP codes in this dataset. Within IL, it ranks 1,097 of 1,548.
Learn more
local microclimates covers what one yard in Saybrook can differ from the 61770 normal. zone vs. frost date covers why Zone 6a and Saybrook's frost date answer different questions.