Mendham, NJ 07970 Frost Dates
07970, near Mendham, NJ: the frost window
Around 04/17 is the usual last spring frost, about 232 days away. Fall's first freeze usually shows up around 10/23, roughly 189 days after the last spring frost.
Zone 6b (-5 to 0°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 Mendham, not a forecast for this year.
Stretching the season past the first frost
Mendham'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.
The actual range around Mendham's last frost
04/17 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/04 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.
Mendham against the rest of the dataset
Mendham's growing season runs about 189 days, ranking 21,545 of 40,283 US ZIP codes measured here, longest to shortest. Within NJ, it ranks 646 of 906.
Learn more
Two guides worth reading on 07970: the frost range, on how to read the range around Mendham's dates instead of trusting one, and local microclimates, on what one yard in Mendham can differ from the 07970 normal.