When Is the Last Frost in Maine?
The average last spring frost in Maine falls between April 27 and May 16 for most ZIP codes, with a statewide median of May 6. At the average date a later frost is still a coin flip, so tender plants wait for the safer 90% date.
| City | Last frost | 90% safe after | First frost | Growing season |
|---|---|---|---|---|
| Portland | Apr 26 | May 7 | Oct 15 | 170 days |
| Lewiston | Apr 25 | May 6 | Oct 19 | 177 days |
| Bangor | May 4 | May 17 | Oct 4 | 152 days |
| South Portland | Apr 26 | May 7 | Oct 15 | 170 days |
| Auburn | Apr 25 | May 6 | Oct 19 | 177 days |
| Sanford | May 16 | May 29 | Sep 30 | 136 days |
| Biddeford | May 9 | May 22 | Oct 3 | 146 days |
| Westbrook | Apr 26 | May 7 | Oct 15 | 170 days |
| Saco | Apr 26 | May 7 | Oct 15 | 170 days |
| Augusta | Apr 27 | May 7 | Oct 16 | 172 days |
| Ellsworth | May 8 | May 23 | Oct 9 | 152 days |
| Bath | May 10 | May 23 | Oct 6 | 149 days |
| Presque Isle | May 14 | Jun 1 | Sep 26 | 131 days |
| Rockland | Apr 27 | May 9 | Oct 19 | 175 days |
| Belfast | May 7 | May 21 | Oct 5 | 151 days |
| Calais | May 5 | May 18 | Oct 13 | 160 days |
| Eastport | Apr 29 | May 11 | Oct 25 | 178 days |
Last and first frost: 50% (median) dates of the last spring and first fall 32 °F night. 90% safe after: only a 10% chance of a later spring frost. First frost dates in January fall in the following winter. Each city uses the NOAA station nearest the ZIP code closest to its center.
Across all 82 Maine weather stations with frost records, median last frost dates run from April 21 at Woodland, ME to June 2 at Allagash, ME. Elevation, valleys that collect cold air and distance from large water bodies explain most of the spread, so a garden a few miles from a listed city can differ by a week or more. The ZIP code lookup above uses the same NOAA data as the frost date calculator for every US ZIP code.
When Is the First Frost in Maine?
The average first fall frost in Maine arrives between September 26 and October 21 for most ZIP codes, with a median of October 6. Tomatoes, peppers, basil and squash are damaged at 32 °F, so harvest or cover them before then.
Fall frost can come early: Portland has a 10% chance of frost before October 2, Lewiston has a 10% chance of frost before October 5 and Bangor has a 10% chance of frost before September 23. Hardy crops such as kale, spinach and cabbage tolerate light frosts and keep producing after the first frost date.
When to Plant Tomatoes in Maine?
Transplant tomatoes in Maine 1 to 2 weeks after the local average last frost, once nights stay above about 50 °F: May 3 – May 10 in Portland, May 2 – May 9 in Lewiston and May 11 – May 18 in Bangor. Start seeds indoors 6 to 8 weeks before the last frost.
| City | Start seeds indoors | Transplant outdoors | Lowest-risk transplant |
|---|---|---|---|
| Portland | Mar 1 – Mar 15 | May 3 – May 10 | after May 7 |
| Lewiston | Feb 28 – Mar 14 | May 2 – May 9 | after May 6 |
| Bangor | Mar 9 – Mar 23 | May 11 – May 18 | after May 17 |
| South Portland | Mar 1 – Mar 15 | May 3 – May 10 | after May 7 |
| Auburn | Feb 28 – Mar 14 | May 2 – May 9 | after May 6 |
| Sanford | Mar 21 – Apr 4 | May 23 – May 30 | after May 29 |
| Biddeford | Mar 14 – Mar 28 | May 16 – May 23 | after May 22 |
| Westbrook | Mar 1 – Mar 15 | May 3 – May 10 | after May 7 |
| Saco | Mar 1 – Mar 15 | May 3 – May 10 | after May 7 |
| Augusta | Mar 2 – Mar 16 | May 4 – May 11 | after May 7 |
| Ellsworth | Mar 13 – Mar 27 | May 15 – May 22 | after May 23 |
| Bath | Mar 15 – Mar 29 | May 17 – May 24 | after May 23 |
| Presque Isle | Mar 19 – Apr 2 | May 21 – May 28 | after Jun 1 |
| Rockland | Mar 2 – Mar 16 | May 4 – May 11 | after May 9 |
| Belfast | Mar 12 – Mar 26 | May 14 – May 21 | after May 21 |
| Calais | Mar 10 – Mar 24 | May 12 – May 19 | after May 18 |
| Eastport | Mar 4 – Mar 18 | May 6 – May 13 | after May 11 |
Indoors: 6–8 weeks before the average last frost. Outdoors: 1–2 weeks after it. Lowest-risk: after the date with only a 10% chance of a later frost. Rules of thumb; check the 10-day forecast and wait for soil near 60 °F.
Tomatoes stall below about 50 °F at night and are killed by frost, so a week or two of waiting after the average date costs little. The tomato plant care guide covers light, watering and feeding once plants are in the ground.
What Can You Plant in Portland and When?
Portland's average last frost of April 26 anchors its spring planting calendar: peas and spinach go in from March 15, broccoli and lettuce transplants from March 29, and tomatoes, peppers and squash after May 3.
| Crop | Start seeds indoors | Plant outdoors | Frost tolerance |
|---|---|---|---|
| Peas | — | Mar 15 – Mar 29direct sow, 4–6 weeks before last frost | hardy |
| Spinach | — | Mar 15 – Apr 5direct sow, 3–6 weeks before last frost | hardy |
| Radishes | — | Mar 22 – Apr 5direct sow, 3–5 weeks before last frost | hardy |
| Onions (sets) | — | Mar 29 – Apr 12plant, 2–4 weeks before last frost | hardy |
| Potatoes | — | Mar 29 – Apr 12plant, 2–4 weeks before last frost | half-hardy |
| Broccoli & cabbage | Mar 1 – Mar 15 | Mar 29 – Apr 12transplant, 2–4 weeks before last frost | hardy |
| Lettuce | Mar 15 – Mar 29 | Mar 29 – Apr 12transplant, 2–4 weeks before last frost | hardy |
| Beets | — | Mar 29 – Apr 12direct sow, 2–4 weeks before last frost | half-hardy |
| Carrots | — | Apr 5 – Apr 12direct sow, 2–3 weeks before last frost | half-hardy |
| Tomatoes | Mar 1 – Mar 15 | May 3 – May 10transplant, 1–2 weeks after last frost | tender |
| Basil | Mar 1 – Mar 15 | May 3 – May 17transplant, 1–3 weeks after last frost | tender |
| Peppers | Feb 15 – Mar 1 | May 10 – May 17transplant, 2–3 weeks after last frost | tender |
| Eggplant | Feb 15 – Mar 1 | May 10 – May 17transplant, 2–3 weeks after last frost | tender |
| Green beans | — | May 3 – May 17direct sow, 1–3 weeks after last frost | tender |
| Sweet corn | — | May 3 – May 17direct sow, 1–3 weeks after last frost | tender |
| Cucumbers | Mar 29 – Apr 5 | May 3 – May 17transplant, 1–3 weeks after last frost | tender |
| Squash & zucchini | Mar 29 – Apr 5 | May 3 – May 17transplant, 1–3 weeks after last frost | tender |
| Watermelon | Mar 29 – Apr 5 | May 10 – May 17transplant, 2–3 weeks after last frost | tender |
Dates for Portland (last frost Apr 26, NOAA station Portland INTL Jetport, ME, 6 miles from ZIP 04108). General rules of thumb; wait for soil near 50 °F for most seeds and 60 °F for beans, corn and squash.
How Long Is the Growing Season in Maine?
The frost-free growing season in Maine lasts about 131 to 175 days for most ZIP codes, with a median of 152 days. Among the listed cities, Presque Isle has the shortest season at 131 days and Eastport the longest at 178.
Season length decides which varieties ripen: compare it with the “days to maturity” on seed packets, counted from transplanting for tomatoes and peppers. NOAA stations in Maine range from 102 days at Allagash, ME to 185 days at Woodland, ME. Planning beds before the season starts helps in short seasons — a plant spacing calculator for vegetable beds shows how many transplants fit.
What Hardiness Zones Are in Maine?
Maine spans USDA hardiness zones 3b to 7a, with zone 5a the most common. Zones describe winter cold and decide which perennials survive, while frost dates set when to plant annual vegetables and flowers.
The Maine planting zone map with the zone of each city shows how the zones are spread across the state and which plants are hardy in all of them.
Frequently Asked Questions
- When is the last frost in Maine?
- The average last spring frost in Maine falls between April 27 and May 16 for most ZIP codes, with a statewide median of May 6. Among major cities it ranges from April 25 in Lewiston to May 16 in Sanford.
- When is the last frost in Portland, Maine?
- Portland's average last spring frost is April 26, and by May 7 the chance of a later frost drops to 10%. Its first fall frost averages October 15, giving a 170-day growing season (NOAA station Portland INTL Jetport, ME).
- When should you plant tomatoes in Maine?
- Transplant tomatoes in Maine 1 to 2 weeks after the local average last frost, once nights stay above about 50 °F: May 3 – May 10 in Portland, May 2 – May 9 in Lewiston and May 11 – May 18 in Bangor. Start seeds indoors 6 to 8 weeks before the last frost.
- When is the first frost in Maine?
- The average first fall frost in Maine arrives between September 26 and October 21 for most ZIP codes, with a median of October 6. Harvest tender crops such as tomatoes, peppers and basil before then or cover them on cold nights.
- How long is the growing season in Maine?
- The frost-free growing season in Maine lasts about 131 to 175 days for most ZIP codes, with a median of 152 days, from 131 days in Presque Isle to 178 days in Eastport.
Frost data: NOAA National Centers for Environmental Information, 1991–2020 U.S. Climate Normals (32 °F freeze dates by probability). ZIP code and city locations and populations: U.S. Census Bureau Gazetteer files and Vintage 2024 population estimates. Planting windows are general rules of thumb. PlantoScan is not affiliated with or endorsed by these agencies.