Portland, Maine Weather
Apples hang heavy on the branch. Day 93 of summer. Read this microseason across nine climate regions →
Portland weather forecast — hour by hour, 7-day outlook, NOAA radar
Conditions updated 10:23 AM EDT · Open-Meteo
- TodaySep 21Overcast later17%—69°49°—
- TuesdaySep 22Overcast——62°49°-7°
- WednesdaySep 23Overcast——60°43°-2°
- ThursdaySep 24Overcast——64°44°+4°
- FridaySep 25Overcast45%—70°50°+6°
- SaturdaySep 26Overcast54%—74°53°+4°
- SundaySep 27Overcast43%—74°56°0°
Air quality now AQI 45 · Good
AQI 45 (Good), driven by Ozone. AQI flat over the last 6 hours (within ±3 points). Ozone at AQI 31. Overcast through the UV peak window (cloud cover ~100%) — afternoon ozone should stay flat.
OK No precautions needed for the general population; unusually sensitive individuals may consider limiting prolonged outdoor exertion.
What's driving it
Ozone × UV × Sky
Ozone at AQI 31. Overcast through the UV peak window (cloud cover ~100%) — afternoon ozone should stay flat.
- Present
- AQI 31
- UV peak
- 4.2 at 1 PM
- Sky at peak
- overcast
- Projected peak
- AQI 9
PM × Wind × Precip
PM2.5 at 5.0 µg/m³, PM10 at 5.4 µg/m³ — typical background levels with no transport signature.
- PM2.5/PM10
- 0.93
- Wind
- light
- Recent rain
- 0h in last 6h
- Pattern
- background
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).
September dries up ditches or breaks down bridges.
- Moonrise
- 4:24 PM
- Moonset
- 12:46 AM
- In sign
- ♑︎ Capricorn
Apples hang heavy on the branch
Read this microseason across nine climate regions →
All 72 microseasons on the year wheel →
Portland at a glance
- Today vs. normal: Today averages 59°F (high 69°F, low 49°F), about the 59°F normal for Sep 21
- Last frost: April 26 (1991–2020 median, NOAA station 4 km away)
- Microseason: Sep 21–25
- Planting calendar: September — plant garlic (overwinter); harvest tomatoes, peppers, beans, summer squash, winter squash
16-Day Forecast — Portland
- Mon69°49°17%
- Tue62°49°0%
- Wed60°43°0%
- Thu64°44°4%
- Fri70°50°45%
- Sat74°53°54%
- Sun74°56°43%
- Mon70°52°39%
- Tue66°51°16%
- Wed67°50°22%
- Thu66°57°26%
- Fri72°54°20%
- Sat61°47°13%
- Sun64°51°13%
- Mon67°61°21%
- Tue61°45°24%
Forecast data from Open-Meteo (CC BY 4.0).
Live wind & temperature near Portland
Interactive wind and temperature map centered on Portland — it loads in your browser. Open the full weather map.
Right now in the garden
Fall planting + final harvests
As of September 21, the season's first frost (typically October 15) is approaching. Pick what frost-tender plants still carry before the next cold front. This city's planting calendar for September: plant garlic (overwinter); harvest tomatoes, peppers, beans, summer squash, and winter squash.
Sun & seasons in Portland
Portland sits in Cumberland County, where the year’s longest day runs 15h 27m of daylight and its shortest just 8h 55m — a swing of +6h 31m between the June and December solstices. Clocks spring forward on Sunday, March 8, 2026 and fall back on Sunday, November 1, 2026.
Portland is the state’s largest city. The nearest town Portland tracks is Turner, roughly 40 miles to the N.
Air quality in Portland
Air quality in Portland’s county has held roughly steady since 2020; its cleanest year on record was 2021 (median AQI 36). See the full air-quality history for Portland.
Planting calendar
| Month | Plant | Harvest |
|---|---|---|
| April | lettuce, peas, spinach, radishes | radishes |
| May | lettuce, peas, spinach, radishes | lettuce, spinach, radishes |
| June | tomatoes, peppers, beans, squash | lettuce, peas, spinach, radishes |
| July | tomatoes, peppers, beans, squash, fall brassicas, carrots | lettuce, peas, spinach, summer squash, garlic |
| August | — | tomatoes, peppers, beans, summer squash, garlic |
| September | garlic (overwinter) | tomatoes, peppers, beans, summer squash, winter squash |
| October | — | tomatoes, peppers, beans, summer squash, winter squash, fall brassicas, carrots |
| November | — | fall brassicas, carrots |
A year in weather
July is Portland's warmest stretch (~70°F) and January its coldest (~24°F); precipitation crests in October at 5.3 inches and ebbs in July to 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
Similar climates South Portland, ME, Westbrook, ME, Falmouth Foreside, ME
In Portland, NOAA NCEI 1991-2020 normals put January near 24°F and July near 70°F — a 46°F seasonal arc — with about 48.1 inches of precipitation over 80 rainy or snowy days.
No season owns Portland's rain: October reaches 5.3 inches across 6.8 days and July keeps 3.4 inches on 6.7, an even spread through Portland's year. That lines Portland up with places like South Portland, ME, Westbrook, ME and Falmouth Foreside, ME, fed by overlapping storm tracks.
Around April 26, Portland sheds its freezing nights — kale, peas, spinach, and parsnips go into Portland's beds. Portland's heat-lovers — tomatoes, peppers, squash — hold off until Portland's frost risk clears, 10-14 days on. The season ends by October 15 in Portland, once hard frosts set back in. That date is a median: Portland freezes sooner in half of years.
Similar climates: South Portland, ME, Westbrook, ME, Falmouth Foreside, ME, Cumberland Center, ME, South Windham, ME.
Frequently asked
- When does it freeze in Portland?
- In Portland, expect the last spring frost near April 26; Portland's first autumn frost comes around October 15.
- What is the rainy season in Portland?
- Portland sees its heaviest rain in October (around 5.3 inches), part of roughly 48 inches a year.
- What is the warmest month in Portland?
- July is Portland's warmest month, averaging about 70°F.
- What is the coldest month in Portland?
- Portland bottoms out in January, with a mean near 24°F.
- When can I start a vegetable garden in Portland?
- Portland's last frost (April 26) cues hardy greens; in Portland, hold heat-lovers two weeks past.
- How many rainy days does Portland get?
- Expect roughly 80 wet days a year in Portland.
- What hardiness zone is Portland?
- Portland's USDA zone comes from its January mean (24°F); enter the ZIP on the USDA lookup for the number.
- What is the 10-day forecast for Portland?
- 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 Portland?
- See this week's day-by-day rain chances for Portland in the daily forecast above, and the next 24 hours in the hourly chart.
- What is the weather like right now in Portland?
- Current conditions for 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 Portland forecast updated?
- The 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 Portland?
- Today's sunrise and sunset times for 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 Portland?
- The next few days in Portland's forecast are the most reliable; accuracy declines beyond about a week as weather-model uncertainty grows.
Portland sits at 43.7°N; its climate zone is warm-summer humid continental (Köppen approximation).
ZIP codes in Portland
- 04019
- 04101
- 04102
- 04103
- 04104
- 04108
- 04109
- 04112
- 04116
- 04122
- 04123
- 04124