Last frost date in South Portland, ME
Expect the last frost in South Portland around April 26. Frost after May 7 happens in only one year out of ten. The first fall frost usually arrives about October 15, which leaves 170 frost-free days. An early freeze before October 2 happens one year in ten.
- Safe after (10% risk)
- May 7
- Average first frost
- Oct 15
- Frost-free season
- 170 days
- Hard freeze (28°F) ends
- Apr 14
Hard freeze likely Fri night, low 27°F
National Weather Service forecast, updated Oct 22, 12:57 UTC
- ThuOct 2233°possible frost
- FriOct 2327°hard freeze
- SatOct 2429°frost
- SunOct 2533°possible frost
- MonOct 2638°
- TueOct 2733°possible frost
- WedOct 2835°possible frost
Planting calendar for South Portland
Windows count forward or back from the average frost dates above. Click a crop for dates across Maine.
TomatoesMay 3–May 17
PumpkinsMay 10–May 24
SunflowersApr 26–May 17
CucumbersMay 10–May 17
CornMay 3–May 17
Sweet potatoesMay 17–May 31
WatermelonMay 10–May 24
Green beansMay 3–May 24
ZucchiniMay 3–May 17
OkraMay 17–May 31
PeppersMay 10–May 24
BasilMay 3–May 17
Butternut squashMay 3–May 17
CantaloupeMay 10–May 24
EggplantMay 10–May 24
PotatoesMar 29–Apr 12
OnionsMar 15–Apr 5
CarrotsApr 5–May 10
LettuceApr 12–May 3
BroccoliMar 29–Apr 12
BeetsMar 29–May 10
PeasMar 15–Mar 29
CabbageMar 29–Apr 12
RadishesMar 22–May 3
Brussels sproutsApr 12–Apr 26
SpinachMar 15–Apr 5
CilantroApr 12–May 3
KaleMar 29–Apr 12
Collard greensMar 29–Apr 12
TurnipsMar 29–Apr 12
DillApr 26–May 10
CeleryMay 3–May 10
CauliflowerApr 12–Apr 26
LeeksApr 12–Apr 26
Swiss chardApr 12–May 10
ParsleyApr 12–May 3
Tulip bulbsOct 1–Nov 5
GarlicSep 24–Oct 29
Daffodil bulbsSep 17–Oct 29
StrawberriesMar 29–Apr 12
AsparagusMar 29–Apr 12Frost probabilities
| Threshold | Spring, 90% chance later | Spring, 50% | Spring, 10% | Fall, 10% chance earlier | Fall, 50% | Fall, 90% |
|---|---|---|---|---|---|---|
| Light frost, 32°F | Apr 16 | Apr 26 | May 7 | Oct 2 | Oct 15 | Oct 30 |
| Hard freeze, 28°F | Apr 3 | Apr 14 | Apr 25 | Oct 14 | Oct 27 | Nov 9 |
Read the spring 10% column as the date after which only one year in ten still gets frost. That is the safer date for tomatoes, peppers and basil.
Where these numbers come from
NOAA station Portland International Jetport (USW00014764) sits 1.5 miles from the center of South Portland at 45 feet. Its averages cover 1991 to 2020. Low spots, valleys and open fields can keep getting frost a week or two after the station stops; city centers and lakeshores usually get less of it.
Questions
When is the last frost in South Portland, ME?
The average last frost date in South Portland is April 26, based on NOAA 1991–2020 climate normals. There is a 10% chance of frost after May 7.
When is the first frost in South Portland?
The first frost in fall usually comes around October 15. One year in ten it arrives before October 2.
How long is the growing season in South Portland?
About 170 days between the average last and first frost.
When should I plant tomatoes in South Portland?
Plant tomato seedlings outside from May 3 to May 17. Start seeds indoors six to eight weeks earlier.