When is the last frost in Portland, ME?

The average (50% probability) last spring frost in Portland is April 26, based on NOAA 1991–2020 normals. A 1-in-10 risk remains until May 7.

When is the first frost in Portland?

The average first fall frost in Portland is October 15, with a growing season of about 170 days.

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Portland, Maine frost dates

Average last spring frost: April 26. Average first fall frost: October 15. That gives a growing season of about 170 days. For frost-tender plants, a safer planting date is May 7, after which a freeze happens in only 1 year in 10.

Last frost (50%)

Apr 26

1-in-10 risk after May 7

First frost (50%)

Oct 15

1-in-10 risk before Oct 2

Growing season

170 days

median frost-free days

Hard freeze (28°F)

Apr 14

median last 28°F in spring

Frost risk by date

Chance of frost	Spring: frost after	Fall: frost before
90%	April 16	October 30
70%	April 22	October 21
50%	April 26	October 15
30%	May 1	October 9
10%	May 7	October 2

Read the spring column like this: there is a 10% chance of a 32°F freeze after May 7. These are NOAA probabilities for the Portland International Jetport weather station (USW00014764, elevation 14 m), 1991–2020.

Portland vegetable planting calendar

Dates count from the 50% last-frost date (April 26). For tomatoes, peppers and other frost-tender crops, waiting until the 10% date (May 7) is the cautious choice.

Crop	Start seeds indoors	Plant out
Beans	Apr 5	May 3 (usually sown directly in the garden)
Broccoli	Feb 15	Mar 29
Brussels sprouts	Feb 15	Mar 29
Cabbage	Feb 8	Mar 22
Cauliflower	Mar 1	Apr 12
Sweet corn	Mar 29	Apr 26 (usually sown directly in the garden)
Cucumbers	Apr 12	May 3
Kale	Feb 8	Mar 22
Leeks	Jan 11	Mar 22
Lettuce	Mar 8	Apr 12
Melons	Apr 19	May 10
Onions	Jan 4	Mar 15 (from seed; sets and transplants go out at the same time)
Peas	Mar 1	Mar 29 (usually sown directly in the garden)
Peppers	Mar 15	May 10
Squash	Apr 19	May 10
Tomatoes	Mar 1	Apr 26

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 October 15. There's a 1-in-10 chance it comes before October 2. 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 October 27.

Nearby cities

City	Last frost (50%)	First frost (50%)	Distance
Manchester, NH	Apr 21	Oct 19	~121 km
Boston, MA	Apr 4	Nov 9	~154 km
Bangor, ME	May 4	Oct 4	~174 km
Worcester, MA	Apr 23	Oct 21	~198 km
Providence, RI	Apr 11	Oct 30	~233 km
Burlington, VT	Apr 29	Oct 15	~246 km

More: all Maine frost dates