Marlborough, MA 01720 Frost Dates
Frost dates for Marlborough, MA, ZIP 01720
Typically, the last spring freeze lands around 05/02, roughly 247 days out. The first fall frost typically arrives around 10/06, about 156 frost-free days later.
Marlborough sits in USDA Zone 6b (-5 to 0°F average annual minimum). The dates above are NOAA's 1991-2020 normal at the nearest reporting station, a 30-year average, not a forecast.
What to do before the first frost
Zone 6b around Marlborough has about 6 weeks left before the first fall frost — that's the usual window to get a cold frame up if you want to keep harvesting past it.
Why 05/02 isn't a guarantee
05/02 is the middle of 30 years of NOAA records, not a promise. Plant by 04/22 and you're betting against frost in roughly 9 years out of 10. 05/16 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Marlborough compares
About 156 days separate Marlborough's last and first frost, putting it 33,516 of 40,283 ZIP codes nationally. Within MA, it ranks 616 of 712.
Learn more
zone vs. frost date explains why Zone 6b and Marlborough's frost date answer different questions, and the frost range explains how to read the range around Marlborough's dates instead of trusting one.