When is the last frost in Boston, MA?

The average (50% probability) last spring frost in Boston is April 4, based on NOAA 1991–2020 normals. A 1-in-10 risk remains until April 17.

When is the first frost in Boston?

The average first fall frost in Boston is November 9, with a growing season of about 218 days.

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Boston, Massachusetts frost dates

Average last spring frost: April 4. Average first fall frost: November 9. That gives a growing season of about 218 days. For frost-tender plants, a safer planting date is April 17, after which a freeze happens in only 1 year in 10.

Last frost (50%)

Apr 4

1-in-10 risk after Apr 17

First frost (50%)

Nov 9

1-in-10 risk before Oct 29

Growing season

218 days

median frost-free days

Hard freeze (28°F)

Mar 28

median last 28°F in spring

Frost risk by date

Chance of frost	Spring: frost after	Fall: frost before
90%	March 25	November 22
70%	April 1	November 14
50%	April 4	November 9
30%	April 8	November 3
10%	April 17	October 29

Read the spring column like this: there is a 10% chance of a 32°F freeze after April 17. These are NOAA probabilities for the Boston Logan International Airport weather station (USW00014739, elevation 4 m), 1991–2020.

Boston vegetable planting calendar

Dates count from the 50% last-frost date (April 4). For tomatoes, peppers and other frost-tender crops, waiting until the 10% date (Apr 17) is the cautious choice.

Crop	Start seeds indoors	Plant out
Beans	Mar 14	Apr 11 (usually sown directly in the garden)
Broccoli	Jan 24	Mar 7
Brussels sprouts	Jan 24	Mar 7
Cabbage	Jan 17	Feb 28
Cauliflower	Feb 7	Mar 21
Sweet corn	Mar 7	Apr 4 (usually sown directly in the garden)
Cucumbers	Mar 21	Apr 11
Kale	Jan 17	Feb 28
Leeks	Dec 20	Feb 28
Lettuce	Feb 14	Mar 21
Melons	Mar 28	Apr 18
Onions	Dec 13	Feb 21 (from seed; sets and transplants go out at the same time)
Peas	Feb 7	Mar 7 (usually sown directly in the garden)
Peppers	Feb 21	Apr 18
Squash	Mar 28	Apr 18
Tomatoes	Feb 7	Apr 4

Offsets from Oregon State University Extension's seed-starting table. "Plant out" means transplant, or sow directly for crops usually grown from seed.

Fall frost and season extension

The first fall freeze usually arrives around November 9. There's a 1-in-10 chance it comes before October 29. Harvest tender crops such as basil, tomatoes, peppers and squash before then, or cover them on cold nights. Cool-season crops like kale, cabbage and Brussels sprouts handle light frost, and often taste sweeter after it. A hard freeze (28°F) typically comes around November 21.

Nearby cities

City	Last frost (50%)	First frost (50%)	Distance
Worcester, MA	Apr 23	Oct 21	~71 km
Manchester, NH	Apr 21	Oct 19	~73 km
Providence, RI	Apr 11	Oct 30	~79 km
Hartford, CT	Apr 21	Oct 16	~145 km
Portland, ME	Apr 26	Oct 15	~154 km
Albany, NY	Apr 27	Oct 15	~233 km

More: all Massachusetts frost dates