Rocky Hill, NJ 08504 Frost Dates
08504, near Rocky Hill, NJ: the frost window
Around 04/25 is the usual last spring frost, about 240 days away. Fall's first freeze usually shows up around 10/16, roughly 173 days after the last spring frost.
Zone 7a (0 to 5°F average annual minimum) comes from the USDA Plant Hardiness Zone Map; the frost dates above are the 1991-2020 normal at the nearest reporting NOAA station for Rocky Hill, not a forecast for this year.
Stretching the season past the first frost
Rocky Hill'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.
How much risk comes with planting early here
04/25 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/12 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/12 and only about 1 year in 10 sees frost after that.
Rocky Hill against the rest of the dataset
About 173 days separate Rocky Hill's last and first frost, putting it 28,020 of 40,283 ZIP codes nationally. Within NJ, it ranks 854 of 906.
Learn more
Two guides worth reading on 08504: zone vs. frost date, on why Zone 7a and Rocky Hill's frost date answer different questions, and the frost range, on how to read the range around Rocky Hill's dates instead of trusting one.