Marlborough, MA 01815 Frost Dates
01815, near Marlborough, MA: the frost window
Around 05/02 is the usual last spring frost, about 247 days away. Fall's first freeze usually shows up around 10/06, roughly 156 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Marlborough 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
Marlborough's growing season runs out in roughly 6 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
Why 05/02 isn't a guarantee
05/02 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/22 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/16 and only about 1 year in 10 sees frost after that.
Marlborough against the rest of the dataset
At roughly 156 frost-free days, Marlborough places 33,525 of 40,283 ZIP codes in this dataset. Within MA, it ranks 625 of 712.
Learn more
Two guides worth reading on 01815: the frost range, on how to read the range around Marlborough's dates instead of trusting one, and local microclimates, on what one yard in Marlborough can differ from the 01815 normal.