Duncan, NE 68634 Frost Dates
68634, near Duncan, NE: the frost window
Typically, the last spring freeze lands around 04/21, roughly 236 days out. Fall's first freeze usually shows up around 10/15, roughly 174 days after the last spring frost.
Duncan 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.
Stretching the season past the first frost
Duncan's growing season runs out in roughly 7 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
Why 04/21 isn't a guarantee
04/21 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/07 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/05 and only about 1 year in 10 sees frost after that.
Duncan against the rest of the dataset
At roughly 174 frost-free days, Duncan places 27,604 of 40,283 ZIP codes in this dataset. Within NE, it ranks 133 of 605.
Learn more
Two guides worth reading on 68634: zone vs. frost date, on why Zone 5b and Duncan's frost date answer different questions, and the frost range, on how to read the range around Duncan's dates instead of trusting one.