Boston, MA Frost Dates: Last Spring and First Fall Frost

In a typical year the final freeze of spring reaches Boston around April 4, and the first freeze of autumn returns around November 9. NOAA's normals call the frost-free stretch between them 218 days long.

Because half of all years do worse than the typical date, the dates that matter for tender plants are the late spring date, April 17, and the early fall date, October 29, each of which one year in ten fails to beat. At 218 days, Boston's typical season sits close to the 229 days median of the 100 cities on these pages.

NOAA measured them at Boston Logan International AP (station USW00014739), about 1.6 miles north of the Census Bureau's internal point for Boston and about 10 feet above sea level.

When is the last frost in Boston?

NOAA gives March 25 as the date a spring freeze is still ahead in nine years out of ten, April 4 as the date it is still ahead in half of them, and April 17 as the date only one year in ten passes.

Only 23 days separate the earliest and latest of these dates, a tighter run than most of the 100 cities here, so the typical date is a fairly dependable guide in Boston.

First fall frost in Boston

Expect the first freeze of fall by November 9 in a typical year. One year in ten brings it by October 29, and nine in ten have had it by November 22.

Fall frost keeps to a tight calendar in Boston: 24 days from the 10% date to the 90% date, less than in most of the 100 cities here.

The growing season in Boston

Neither long nor short next to the other cities here. A short year costs just 17 days against a typical one (201 days against 218 days), so a season-length plan for Boston holds up in most years.

NOAA counts these days from its own simulations, so they will not equal the number of days between the two typical dates exactly. A night at or below 32°F happens in 100% of years at this station, so frost is a yearly event here.

28°F dates in Boston

The two freezes sit close together here. The typical hard freeze reaches Boston on November 21, 12 days after the first frost, and ends on March 28, 7 days ahead of the last. One spring in ten still has a 28°F night on or after April 6, and one fall in ten sees the first by November 8.

Planting dates for Boston, counted from the frost dates

Counting from April 4, University of New Hampshire Extension puts cabbage transplants out on March 7 and lettuce from March 7 to March 14, ahead of the last frost, and holds peppers until April 18 and beans until April 4 or later. The University of New Hampshire Extension sheet gives peas no frost count at all; sow them as soon as the soil thaws.

The late date comes 13 days after the typical one; choose it for plants you cannot cover.

Boston's first frost leaves room for only 32 of the 34 fall crops, counting back NC State Extension's days to harvest and University of Georgia Extension's harvest allowance of 18 days; for the other 2 the last planting day falls before July. Of the crops that fit, collard greens is the slowest: 118 days from planting to the early frost, which makes July 3 its last day.

Worked example: tomatoes in Boston

Take tomatoes in Boston. The University of New Hampshire Extension rule is to set transplants out one to two weeks after the last frost. From April 4, the typical date, that means April 11 to April 18; from April 17, the late date, it means April 24 to May 1, a delay of 13 days.

Indoors, tomato seeds go in six to eight weeks ahead of set-out; from the first day of the late window that is February 27 to March 13.

From the last set-out day to the early first frost on October 29 is 181 days. NC State Extension gives 75 to 85 days, and the longer figure still fits with 96 days to spare.

Where Boston's numbers are measured

The station is 1.6 miles north of the Census Bureau's internal point for Boston, close enough that its record is the natural reference for the city.

At about 10 feet, it ranks above 1 and below 97 of the 100 stations used for these pages. NOAA flags this station's record as standard, the code S, for the data behind its 50% last-frost value.

Because the Census file has no elevation for Boston, we cannot say how far your yard is above or below this station. When yours is clearly higher or lower, open the nearby stations in the frost dates tool and favor the colder one.

How Boston's frost dates compare

Of the cities on these pages, Worcester, MA is closest to Boston at 41 miles, with two more farther out; none is a close neighbor. Note that the Worcester station stands 990 feet higher than Boston's.

• Worcester, MA lies 41 miles west of Boston. Typical last frost April 23, first frost October 21, 181 days between; spring frost lingers 19 days longer than in Boston, and it has 37 days less without frost.
• Yonkers, NY, 176 miles to the south-west: last frost April 20, first frost October 26, 189 days frost-free; its last frost comes 16 days after Boston's, and it has 29 days less without frost.
• New York, NY, 190 miles to the south-west: last frost April 1, first frost November 19, 233 days frost-free; spring frost ends about when it does in Boston, and the frost-free season is 15 days longer than Boston's.

Next steps for Boston gardeners

Start with the spring planting planner for the whole crop list counted from these dates, and the fall planting planner for the last planting days. The frost dates tool shows every level of risk at this station, and the hardiness zone lookup covers winter survival for shrubs and perennials.

All the cities on these pages are listed by state on the city frost dates index.

Where these numbers come from

Every frost and freeze date comes from the station's entry in NOAA's U.S. Climate Normals for 1991–2020 (doi:10.25921/4ek7-fk11), with no adjustment, and NOAA's documentation explains what each probability means. The city and its internal point come from the Census Bureau's 2024 Gazetteer of places, and the ranking by size from the Census Bureau's Vintage 2024 city and town population estimates, which put Boston at 673,458 people.

The planting dates apply the count rules in University of New Hampshire Extension, NC State Extension and University of Georgia Extension to this station's dates, with nothing added. See how we source every figure for the checks behind them.

Frost dates are long-term odds, not a forecast. Before you plant, check the local forecast for the coming week, and keep row cover or old sheets handy for the nights the odds get wrong.