Port Royal, SC 29920 Frost Dates
29920, near Port Royal, SC: the frost window
Typically, the last spring freeze lands around 03/03, roughly 187 days out. Fall's first freeze usually shows up around 12/09, roughly 282 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Port Royal in Zone 9b (25 to 30°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
Port Royal's growing season runs out in roughly 15 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
03/03 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 02/02 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 03/20 and only about 1 year in 10 sees frost after that.
Port Royal against the rest of the dataset
Port Royal's growing season runs about 282 days, ranking 4,774 of 40,283 US ZIP codes measured here, longest to shortest. Within SC, it ranks 21 of 519.
Learn more
Two guides worth reading on 29920: the frost range, on how to read the range around Port Royal's dates instead of trusting one, and local microclimates, on what one yard in Port Royal can differ from the 29920 normal.