Delta, IA 52550 Frost Dates
Delta, IA: when does the frost end?
Around 04/21 is the usual last spring frost, about 236 days away. Fall's first freeze usually shows up around 10/16, roughly 176 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Delta in Zone 5b (-15 to -10°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
Stretching the season past the first frost
With roughly 7 weeks until Delta's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
The actual range around Delta's last frost
04/21 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/08 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/04 and only about 1 year in 10 sees frost after that.
Delta against the rest of the dataset
At roughly 176 frost-free days, Delta places 26,636 of 40,283 ZIP codes in this dataset. Within IA, it ranks 156 of 1,042.
Learn more
Before leaning on 52550's figures: zone vs. frost date explains why Zone 5b and Delta's frost date answer different questions, while the frost range explains how to read the range around Delta's dates instead of trusting one.