Cambridge, MA 02139 Frost Dates
02139, near Cambridge, MA: the frost window
Typically, the last spring freeze lands around 04/19, roughly 234 days out. Fall's first freeze usually shows up around 10/23, roughly 185 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 Cambridge, not a forecast for this year.
Stretching the season past the first frost
Cambridge'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
04/19 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/06 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/03 and only about 1 year in 10 sees frost after that.
Cambridge against the rest of the dataset
At roughly 185 frost-free days, Cambridge places 23,020 of 40,283 ZIP codes in this dataset. Within MA, it ranks 172 of 712.
Learn more
Two guides worth reading on 02139: local microclimates, on what one yard in Cambridge can differ from the 02139 normal, and zone vs. frost date, on why Zone 6b and Cambridge's frost date answer different questions.