Maine frost dates

Average last spring and first fall frost dates for Maine’s largest cities, with each city’s USDA hardiness zone.

Reviewed October 2026

Among Maine’s 20 largest cities, the average last spring frost ranges from Apr 25 in Lewiston to May 16 in Sanford. Elevation, distance from the coast and city heat all shift the date, so use your own ZIP code below for the closest match.

City	Average last spring frost	Average first fall frost	Frost-free days	Hardiness zone	Weather station used
Portland	Apr 26	Oct 15	172	6a	Portland Intl Jetport, ME, 6 mi
Lewiston	Apr 25	Oct 19	177	5b	Lewiston, ME, 2 mi
Bangor	May 4	Oct 4	153	5a	Bangor Intl Airport, ME, 3 mi
South Portland	Apr 26	Oct 15	172	6a	Portland Intl Jetport, ME
Auburn	Apr 25	Oct 19	177	5b	Lewiston, ME, 2 mi
Sanford	May 16	Sep 30	137	5b	Sanford 2 Nnw, ME, 3 mi
Biddeford	May 9	Oct 3	147	5b–6a	Kennebunkport, ME, 7 mi
Westbrook	Apr 26	Oct 15	172	5b–6a	Portland Intl Jetport, ME, 5 mi
Saco	Apr 26	Oct 15	172	5b–6a	Portland Intl Jetport, ME, 10 mi
Augusta	Apr 27	Oct 16	172	5b	Augusta State Airport, ME, 3 mi
Waterville	May 2	Oct 10	161	5b	Waterville Trtmt Plt, ME
Brewer	May 4	Oct 4	153	5a	Bangor Intl Airport, ME, 4 mi
Ellsworth	May 8	Oct 9	154	5b	E Surry, ME, 6 mi
Bath	May 10	Oct 6	149	5b–6a	Bath, ME
Presque Isle	May 14	Sep 26	135	4a	Presque Isle, ME, 2 mi
Old Town	May 13	Sep 28	138	5a	Old Town 2 W, ME, 3 mi
Caribou	May 7	Oct 1	147	4a	Caribou Muni Airport, ME, 4 mi
Rockland	Apr 27	Oct 19	175	5b–6a	W Rockport 1 Nnw, ME, 5 mi
Belfast	May 7	Oct 5	151	5b	Belfast, ME, 3 mi
Gardiner	May 1	Oct 11	163	5b	Gardiner, ME, 2 mi

Frost dates are the dates after (spring) or before (fall) which the chance of a 32°F freeze is below 50%, from NOAA’s 1991–2020 U.S. Climate Normals for the weather station nearest each city’s center. Zones are from the 2023 USDA Plant Hardiness Zone Map for the ZIP codes around each city; a range means nearby ZIP codes differ. Cities are the 20 largest by Census Bureau 2024 population estimates.

An average is not a guarantee. There’s still about a 1 in 2 chance of frost after the average last spring date. Many gardeners wait an extra week or two before setting out tomatoes, peppers and basil, and keep covers handy.

Planting dates for Portland

Timed from Portland’s average last frost of Apr 26, using University of New Hampshire Extension’s planting guidance. For your exact dates, enter your ZIP code in the calendar below.

Crop	Start seeds indoors	Plant outside
Tomatoes	Mar 8 to Mar 22	May 3 to May 10
Peppers	Mar 1 to Mar 15	May 10
Lettuce	Feb 22 to Mar 1	Mar 29 to Apr 5
Broccoli	Feb 15 to Mar 1	Mar 29 to Apr 12
Cucumbers	Apr 5 to Apr 12	May 3 to May 10
Basil	Mar 15 to Mar 29	May 10

When to plant, for your garden

Your seed-starting and planting dates, timed from your last spring frost. Full calendar, 12 crops.

ZIP code

Last frost date

Enter your ZIP code to look up your average last frost date and hardiness zone, or type the date in yourself.

Frost dates: NOAA U.S. Climate Normals, 1991–2020. Hardiness zones: USDA Plant Hardiness Zone Map, 2023, ZIP code data from PRISM Group, Oregon State University, prism.oregonstate.edu, accessed Oct. 20, 2026.

More about frost dates

How to find your last frost date, and what your zone means · Full planting calendar · How to start seeds indoors

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