Monmouth, IL 61423 Frost Dates
When can you plant in Monmouth, IL?
Around 04/20 is the usual last spring frost, about 235 days away. The first fall frost typically arrives around 10/19, about 180 frost-free days later.
Monmouth 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
About 7 weeks of growing season left in Monmouth before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
How much risk comes with planting early here
04/20 is the middle of 30 years of NOAA records, not a promise. Plant by 04/06 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 Monmouth compares
About 180 days separate Monmouth's last and first frost, putting it 24,826 of 40,283 ZIP codes nationally. Within IL, it ranks 956 of 1,548.
Learn more
the frost range covers how to read the range around Monmouth's dates instead of trusting one. local microclimates covers what one yard in Monmouth can differ from the 61423 normal.