Portland weather in September: Portland, Maine: normal highs, lows, rain and records for September
Portland in September has a normal high of 71°F and a normal low of 52°F, a daily mean of 62°F, falling from 76°F on the 1st to 66°F by the 30th. Measurable precipitation falls on 9 days in a normal September, 3.77 inches in all. (NOAA 1991-2020 normals)
In metric: a normal high of 22°C and low of 11°C, 96 mm of precipitation in September.
- NOAA stationPortland International Jetport
- Station IDUSW00014764
- Location43.65°N 70.30°W
- Elevation45 ft (14 m)
- From the center6 miles
- Population69,568
- Jan 32° 16°
- Feb 35° 17°
- Mar 42° 26°
- Apr 54° 35°
- May 64° 46°
- Jun 74° 55°
- Jul 80° 61°
- Aug 79° 60°
- Sep 71° 52°
- Oct 60° 41°
- Nov 48° 32°
- Dec 38° 22°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
How warm is Portland in September?
The normal high is 71°F and the normal low 52°F, for a daily mean of 61.6°F. September is 7.6°F cooler than August and 11.3°F warmer than October. September is the 4th warmest month of the year in Portland and the 7th wettest. Across the month the normal high falls 10°F, from 76°F on September 1 to 66°F on September 30. From one year to the next September's mean temperature typically moves about 2.1°F either way (NOAA's standard deviation), so roughly two Septembers in three average between 60°F and 64°F.
Bars above: each day's normal high to low. Columns below: the chance of 0.01 inch or more of precipitation that day, on a scale of 0 to 100% (highest 33%).
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in |
|---|---|---|---|---|
| September 1 | 76°F | 57°F | 30% | 16% |
| September 8 | 74°F | 55°F | 30% | 17% |
| September 15 | 72°F | 53°F | 31% | 17% |
| September 22 | 69°F | 50°F | 31% | 19% |
| September 30 | 66°F | 47°F | 33% | 20% |
Every day of September: normal high, low and chance of precipitation (warmest afternoon September 1, coldest night September 30)
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in | Daylight |
|---|---|---|---|---|---|
| September 1 | 76°F | 57°F | 30% | 16% | 13 h 20 min |
| September 2 | 76°F | 57°F | 30% | 16% | 13 h 10 min |
| September 3 | 76°F | 56°F | 30% | 16% | 13 h 10 min |
| September 4 | 75°F | 56°F | 30% | 16% | 13 h 10 min |
| September 5 | 75°F | 56°F | 30% | 16% | 13 h |
| September 6 | 75°F | 56°F | 30% | 16% | 13 h |
| September 7 | 74°F | 55°F | 30% | 17% | 13 h |
| September 8 | 74°F | 55°F | 30% | 17% | 13 h |
| September 9 | 74°F | 55°F | 30% | 17% | 12 h 50 min |
| September 10 | 73°F | 54°F | 30% | 17% | 12 h 50 min |
| September 11 | 73°F | 54°F | 30% | 17% | 12 h 50 min |
| September 12 | 73°F | 54°F | 30% | 17% | 12 h 40 min |
| September 13 | 72°F | 53°F | 30% | 17% | 12 h 40 min |
| September 14 | 72°F | 53°F | 31% | 17% | 12 h 40 min |
| September 15 | 72°F | 53°F | 31% | 17% | 12 h 30 min |
| September 16 | 71°F | 52°F | 31% | 18% | 12 h 30 min |
| September 17 | 71°F | 52°F | 31% | 18% | 12 h 30 min |
| September 18 | 70°F | 51°F | 31% | 18% | 12 h 30 min |
| September 19 | 70°F | 51°F | 31% | 18% | 12 h 20 min |
| September 20 | 70°F | 51°F | 31% | 18% | 12 h 20 min |
| September 21 | 69°F | 50°F | 31% | 18% | 12 h 20 min |
| September 22 | 69°F | 50°F | 31% | 19% | 12 h 10 min |
| September 23 | 68°F | 49°F | 32% | 19% | 12 h 10 min |
| September 24 | 68°F | 49°F | 32% | 19% | 12 h 10 min |
| September 25 | 68°F | 49°F | 32% | 19% | 12 h 10 min |
| September 26 | 67°F | 48°F | 32% | 19% | 12 h |
| September 27 | 67°F | 48°F | 32% | 20% | 12 h |
| September 28 | 66°F | 47°F | 32% | 20% | 12 h |
| September 29 | 66°F | 47°F | 32% | 20% | 11 h 50 min |
| September 30 | 66°F | 47°F | 33% | 20% | 11 h 50 min |
- Normal high
- 71°FSeptember average
- Normal low
- 52°FSeptember average
- Precipitation
- 3.77 inmonth total
- Days with precipitation
- 90.01 inch or more
- Days at 90°F or more
- 1
- Daylight
- 13 h 20 min to 11 h 50 minSeptember 1 to September 30
- Days at 70°F or more
- 16
- Days at 80°F or more
- 4
- Sunshine
- 78%of clear-sky sunlight (NASA)
Source: NOAA NCEI 1991-2020 daily normals, station USW00014764; monthly normals. Daylight is computed from the place's latitude with NOAA's solar equations.
Does it rain in Portland in September?
On a given September day the chance of 0.01 inch or more is 31% on average, highest around September 30 (33%). In all, 3.77 in falls on 9 days of a normal September, 1 of them with an inch or more.
In a normal September in Portland, 1 days reach 90°F.
Source: NOAA NCEI 1991-2020 daily and monthly normals, station USW00014764.
How humid and windy is Portland in September?
At 3 p.m. the normal temperature is 63°F with 60% relative humidity and a dew point of 48°F; at 6 a.m. it is 50°F with 88% humidity. The wind averages 6.8 mph, most often from the southwest in the afternoon. A dew point under 50°F feels dry.
| Time | Temperature | Dew point | Humidity | Wind | Clear or few clouds |
|---|---|---|---|---|---|
| 6 a.m. | 50°F | 46°F | 88% | 5.2 mph | 56% |
| 9 a.m. | 58°F | 49°F | 71% | 8.1 mph | 55% |
| noon | 63°F | 49°F | 60% | 9.8 mph | 51% |
| 3 p.m. | 63°F | 48°F | 60% | 10.1 mph | 53% |
| 6 p.m. | 57°F | 49°F | 73% | 6.6 mph | 57% |
| 9 p.m. | 54°F | 48°F | 80% | 5.2 mph | 66% |
Source: NOAA NCEI 1991-2020 hourly normals, station USW00014764. Hourly normals exist only for NOAA's first-order stations; a dash where NOAA publishes no value for that hour (the sky at some hours).
What are the records for September in Portland?
The warmest September temperature on Portland's official record (since 1874) is 96°F, on September 3, 1929; the coldest is 23°F, on September 30, 1941. The wettest September brought 10.84 in (2008).
The September mean against the 1991-2020 normal of 61.6°F: 2021 63.3°F (+1.6), 2022 60.3°F (−1.3), 2023 64.1°F (+2.5), 2024 62.1°F (+0.5), 2025 62.5°F (+0.9), 2026 60.7°F (−0.9). 4 of 6 ran warmer than normal.
| September | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 63.3°F | +1.6°F | 4.28 in |
| 2022 | 60.3°F | −1.3°F | 4.20 in |
| 2023 | 64.1°F | +2.5°F | 4.91 in |
| 2024 | 62.1°F | +0.5°F | 1.93 in |
| 2025 | 62.5°F | +0.9°F | 1.88 in |
| 2026 | 60.7°F | −0.9°F | 5.12 in |
Source: records: ACIS, NWS threaded record PWMthr; recent months: ACIS, station USW00014764. Records and recent months use complete months only.
How does September in Portland compare across Maine?
Across the 42 places PlainClimate covers in Maine, September normal highs run from 66°F in Limestone to 73°F in Sanford; Portland's is 71°F.
Source: NOAA NCEI 1991-2020 monthly normals for every station in the state.