Rapids City, IL 61278 Frost Dates
Frost dates for Rapids City, IL, ZIP 61278
Around 04/21 is the usual last spring frost, about 236 days away. The first fall frost typically arrives around 10/17, about 176 frost-free days later.
Rapids City 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 Rapids City has about 7 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
04/21 is the middle of 30 years of NOAA records, not a promise. Plant by 04/07 and you're betting against frost in roughly 9 years out of 10. 05/07 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Rapids City compares
Rapids City's growing season runs about 176 days, ranking 26,551 of 40,283 US ZIP codes measured here, longest to shortest. Within IL, it ranks 1,187 of 1,548.
Learn more
local microclimates explains what one yard in Rapids City can differ from the 61278 normal, and zone vs. frost date explains why Zone 5b and Rapids City's frost date answer different questions.