Waltham, MA 02451 Frost Dates
Frost dates for Waltham, MA, ZIP 02451
Typically, the last spring freeze lands around 04/28, roughly 243 days out. The first fall frost typically arrives around 10/10, about 165 frost-free days later.
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 Waltham, not a forecast for this year.
What to do before the first frost
Zone 6b around Waltham 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.
How much risk comes with planting early here
04/28 is the middle of 30 years of NOAA records, not a promise. Plant by 04/13 and you're betting against frost in roughly 9 years out of 10. 05/12 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Waltham compares
About 165 days separate Waltham's last and first frost, putting it 30,500 of 40,283 ZIP codes nationally. Within MA, it ranks 402 of 712.
Learn more
zone vs. frost date explains why Zone 6b and Waltham's frost date answer different questions, and the frost range explains how to read the range around Waltham's dates instead of trusting one.