South Portland, Maine Weather
Cicadas claim the afternoon. Day 15 of summer. Read this microseason across nine climate regions →
South Portland weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJul 5Overcast——82°61°—
- MondayJul 6Overcast——72°61°-10°
- TuesdayJul 7Rain35%0.48″62°56°-10°
- WednesdayJul 8Overcast18%—79°53°+17°
- ThursdayJul 9Overcast14%—89°62°+10°
- FridayJul 10Overcast45%—83°69°-6°
- SaturdayJul 11Overcast14%—78°58°-5°
AQI 53 (Moderate), driven by PM2.5. AQI up 12 over the last 6 hours (gradual rise). PM2.5 at 15.8 µg/m³ (AQI 63) with a 0.94 fine-to-coarse ratio and 3 mph wind — combustion smoke trapped in calm air, not road dust.
OK No precautions needed for the general population; unusually sensitive individuals may consider limiting prolonged outdoor exertion during the projected peak around 8 PM.
What's driving it
Ozone × UV × Sky
Ozone at AQI 42 now. With UV 7.1 peaking around 1 PM under clear skies, surface ozone likely climbs to AQI 40 around 1 PM.
- Present
- AQI 42
- UV peak
- 7.1 at 1 PM
- Sky at peak
- clear
- Projected peak
- AQI 40
PM × Wind × Precip
PM2.5 at 15.8 µg/m³ (AQI 63) with a 0.94 fine-to-coarse ratio and 3 mph wind — combustion smoke trapped in calm air, not road dust.
- PM2.5/PM10
- 0.94
- Wind
- calm
- Recent rain
- 0h in last 6h
- Pattern
- stagnant smoke
Trends
Seven days of AQI and PM2.5.
Hourly air-quality data from the Copernicus Atmosphere Monitoring Service, charted across the past and next several days. Dashed lines mark the AQI breakpoints at 50 (Good → Moderate) and 100 (Moderate → Unhealthy for Sensitive Groups).
If the first of July be rainy weather, 'twill rain more or less for four weeks together.
- Moonrise
- 11:00 PM
- Moonset
- 10:49 AM
- In sign
- ♓︎ Pisces
Cicadas claim the afternoon
South Portland at a glance
- Today vs. normal: 11°F above the seasonal normal for this latitude
- Last frost: May 8 (climatological average for this latitude)
- Microseason: Jul 1–5
- Planting window: Harvest early potatoes. Begin drying onions on the surface.
ZIP code: 04106
16-Day Forecast — South Portland
- Sun82°61°1%
- Mon72°61°6%
- Tue62°56°35%
- Wed79°53°18%
- Thu89°62°14%
- Fri83°69°45%
- Sat78°58°14%
- Sun75°59°9%
- Mon74°56°17%
- Tue80°57°17%
- Wed91°70°17%
- Thu85°63°27%
- Fri90°60°29%
- Sat93°68°21%
- Sun80°63°26%
- Mon81°63°42%
Forecast data from Open-Meteo (CC BY 4.0).
Right now in the garden
Peak growing season
As of July 5, the growing season is at its peak — frost is months away. Continue succession-planting beans and summer squash. Start fall brassicas (broccoli, cabbage, kale) from seed indoors for transplanting in late summer.
Microseason · July 1–5
Cicadas claim the afternoon
Annual cicada buzz begins, peaking in the heat of the day.
Day 186 of 365 · Wedge 37 of 72
Planting calendar
| Month | Plant | Harvest |
|---|---|---|
| January | — | — |
| February | — | — |
| March | — | — |
| April | — | — |
| May | lettuce, peas, spinach, radishes | lettuce, peas, radishes |
| June | lettuce, peas, spinach, radishes, tomatoes, peppers, beans, squash | lettuce, peas, radishes |
| July | tomatoes, peppers, beans, squash | tomatoes, beans, summer squash |
| August | tomatoes, peppers, beans, squash, fall brassicas, garlic (overwinter), carrots | tomatoes, beans, summer squash |
| September | fall brassicas, garlic (overwinter), carrots | tomatoes, beans, summer squash |
| October | — | winter squash, tomatoes (last) |
| November | — | — |
| December | — | — |
A year in weather
South Portland peaks at about 70°F in July and bottoms near 24°F in January; October brings the heaviest rain (5.3 inches) and July the least (3.4 inches).
| Month | Mean temp | Precip | Rainy days |
|---|---|---|---|
| January | 24° | 3.5″ | 7 |
| February | 26° | 3.5″ | 7 |
| March | 34° | 4.1″ | 7 |
| April | 45° | 4.4″ | 7 |
| May | 55° | 3.7″ | 7 |
| June | 64° | 4.2″ | 7 |
| July | 70° | 3.4″ | 7 |
| August | 69° | 3.6″ | 5 |
| September | 62° | 3.8″ | 5 |
| October | 50° | 5.3″ | 7 |
| November | 40° | 4.3″ | 7 |
| December | 30° | 4.5″ | 8 |
Regional context
Drawing on NOAA NCEI 1991-2020 normals, South Portland's January averages 24°F and July 70°F — 46°F apart — while precipitation totals roughly 48.1 inches over some 80 days.
South Portland's precipitation spreads evenly: October peaks at 5.3 inches on 6.8 wet days, while July holds 3.4 inches over 6.7 — no month dominates South Portland's rain calendar. That even rhythm groups South Portland with places like Portland, ME, Westbrook, ME and Dunstan, ME.
South Portland's growing window opens around late-May, once South Portland's overnight lows stop freezing — sow kale, peas, spinach, and parsnips. In South Portland, warm-season transplants — tomatoes, peppers, basil — wait two weeks past South Portland's frost date. It shuts near early-October, when freezes return to South Portland and tender plants need cover. Within South Portland, cold-air pooling chills low spots by 5-10°F, shifting South Portland's local frost dates.
Similar climates: Portland, ME, Westbrook, ME, Dunstan, ME, Falmouth Foreside, ME, Little Falls, ME.
Frequently asked
- When does it freeze in South Portland?
- South Portland's last spring frost lands near mid-May, and in South Portland the first fall frost follows around mid-October.
- What is the rainy season in South Portland?
- October is the wettest month in South Portland, about 5.3 inches on average; the year totals roughly 48 inches.
- What is the warmest month in South Portland?
- South Portland peaks in July, when the mean runs near 70°F.
- What is the coldest month in South Portland?
- January is South Portland's coldest month, averaging about 24°F.
- When can I start a vegetable garden in South Portland?
- Hardy spring crops go in near mid-May in South Portland; tender peppers and squash wait 10–14 days.
- How many rainy days does South Portland get?
- South Portland averages about 80 days with measurable rain or snow each year.
- What hardiness zone is South Portland?
- With January around 24°F, South Portland's zone reflects that minimum — the USDA ZIP map confirms South Portland's band.
- What is the 10-day forecast for South Portland?
- South Portland's extended outlook — daily high and low temperatures and precipitation chances for each upcoming day — is in the daily forecast above.
- Will it rain this week in South Portland?
- See this week's day-by-day rain chances for South Portland in the daily forecast above, and the next 24 hours in the hourly chart.
- What is the weather like right now in South Portland?
- Current conditions for South Portland and the next 24 hours — temperature, precipitation chance, and wind by the hour — are in the hourly forecast chart above.
- How often is the South Portland forecast updated?
- The South Portland forecast on this page is built from Open-Meteo weather-model data and refreshes regularly through the day.
- When are sunrise and sunset in South Portland?
- Today's sunrise and sunset times for South Portland are in the Almanac section above, along with civil dawn, civil dusk, and day length. Day length is longest near the summer solstice and shortest near the winter solstice.
- How accurate is the weather forecast for South Portland?
- The next few days in South Portland's forecast are the most reliable; accuracy declines beyond about a week as weather-model uncertainty grows.
Climate
The warm-summer humid continental climate of South Portland, Maine carries typical Januarys near 24°F and Julys around 70°F — 46°F of seasonal travel.
Rain and snow bring South Portland roughly 48 inches a year across approximately 80 measurable-precipitation days.
South Portland sits at 43.6°N; that 46°F seasonal swing frames planting windows and frost dates across South Portland.
ZIP codes in South Portland
- 04106