Alton, IN 40157 Frost Dates
Frost dates for Alton, IN, ZIP 40157
The last spring frost here typically falls around 04/19, about 234 days from today. The first fall frost typically arrives around 10/24, about 186 frost-free days later.
The USDA Plant Hardiness Zone Map puts Alton in Zone 7a (0 to 5°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
Zone 7a around Alton has about 8 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
04/19 is the middle of 30 years of NOAA records, not a promise. Plant by 04/04 and you're betting against frost in roughly 9 years out of 10. 05/02 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Alton compares
About 186 days separate Alton's last and first frost, putting it 22,989 of 40,283 ZIP codes nationally. Within IN, it ranks 352 of 927.
Learn more
zone vs. frost date explains why Zone 7a and Alton's frost date answer different questions, and the frost range explains how to read the range around Alton's dates instead of trusting one.