Portsmouth, OH 45699 Frost Dates
45699, near Portsmouth, OH: the frost window
Around 04/17 is the usual last spring frost, about 232 days away. Fall's first freeze usually shows up around 10/25, roughly 191 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Portsmouth in Zone 6b (-5 to 0°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
Portsmouth's growing season runs out in roughly 8 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
How much risk comes with planting early here
04/17 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/03 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.
Portsmouth against the rest of the dataset
At roughly 191 frost-free days, Portsmouth places 20,726 of 40,283 ZIP codes in this dataset. Within OH, it ranks 286 of 1,383.
Learn more
Two guides worth reading on 45699: zone vs. frost date, on why Zone 6b and Portsmouth's frost date answer different questions, and the frost range, on how to read the range around Portsmouth's dates instead of trusting one.