Watertown, MA 02458 Frost Dates
When can you plant in Watertown, MA?
Typically, the last spring freeze lands around 04/19, roughly 234 days out. The first fall frost typically arrives around 10/23, about 185 frost-free days later.
Watertown 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
About 8 weeks of growing season left in Watertown before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
How much risk comes with planting early here
04/19 is the middle of 30 years of NOAA records, not a promise. Plant by 04/06 and you're betting against frost in roughly 9 years out of 10. 05/03 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Watertown compares
Watertown's growing season runs about 185 days, ranking 23,063 of 40,283 US ZIP codes measured here, longest to shortest. Within MA, it ranks 194 of 712.
Learn more
local microclimates covers what one yard in Watertown can differ from the 02458 normal. zone vs. frost date covers why Zone 6b and Watertown's frost date answer different questions.