Altona, IL 61414 Frost Dates
Frost dates for Altona, IL, ZIP 61414
Typically, the last spring freeze lands around 04/28, roughly 243 days out. The first fall frost typically arrives around 10/12, about 165 frost-free days later.
Altona sits in USDA Zone 5b (-15 to -10°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
Zone 5b around Altona has about 6 weeks left before the first fall frost — that's the usual window to get a cold frame up if you want to keep harvesting past it.
How much risk comes with planting early here
04/28 is the middle of 30 years of NOAA records, not a promise. Plant by 04/15 and you're betting against frost in roughly 9 years out of 10. 05/12 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Altona compares
Altona's growing season runs about 165 days, ranking 30,707 of 40,283 US ZIP codes measured here, longest to shortest. Within IL, it ranks 1,497 of 1,548.
Learn more
local microclimates explains what one yard in Altona can differ from the 61414 normal, and zone vs. frost date explains why Zone 5b and Altona's frost date answer different questions.