Portland weather in September

In September, Portland sees average daytime highs of 87°F and overnight lows near 75°F, with 4.3 in of rain across 13.8 wet days and about 12.2 hours of daylight. It is the 4th-warmest and 1st-wettest month of the year here.

Highs ease over the month, from about 88°F in the first days to 85°F by the end. The sky is clear or mostly clear about 47% of the time in September, and the air most often feels miserable.

Daylight stretches from about 12 h 36 min at the start of September to 11 h 48 min by month's end. Set against the rest of the year, September is Portland's 6th-clearest and 12th-windiest month. For the whole year in context, see Portland's year-round climate.

Daytime high
87°
4th warmest
Overnight low
75°
9th coldest
Rainfall
4.3 in
13.8 wet days
Daylight
12 h 12 min
6:19 AM – 6:29 PM
Cloud cover
49%
6th clearest
Wind
9 mph
12th windiest
Solar energy
5.14 kWh/m²
Travel score
4.5
out of 10

Portland is city in Texas, United States.

Density
580/km²
people per km²

Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 88°F in the first days to 85°F by the end.

A typical September day in Portland reaches about 87°F in the afternoon and slips back to 75°F overnight — a 12°F spread between the day's warmth and the night's chill. On most days the high lands between 82°F and 90°F. Set against its neighbours, September runs about 3°F cooler than August and about 6°F warmer than October.

60°70°80°90°151015202530
Avg high (°F)Avg low (°F)
18977
28977
38977
48877
58877
68877
78877
88876
98876
108776
118776
128776
138776
148776
158775
168775
178775
188775
198674
208674
218674
228674
238673
248673
258573
268573
278572
288572
298572
308572

How September really feels in Portland

Once humidity and wind are folded in, September averages 28 days that feel above 90°F and 0 that feel at or below 32°F — the comfort signal a plain temperature reading hides.

Days feeling ≥ 90°F
28
heat index over the day's high
Days feeling ≤ 32°F
0
wind chill below the day's low

The story in September is heat — humidity pushes the afternoon "feels like" well above the raw temperature.

Portland weather by month

How September compares with the rest of the year at a glance. September is the 4th-warmest and 1st-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysDaylight (hours)Travel score
Jan65° / 51°2.16.510.46.5
Feb68° / 54°1.55.2116.9
Mar73° / 60°2.26.211.87.4
Apr78° / 66°2.06.412.67.4
May83° / 73°2.78.813.46.1
Jun87° / 77°2.910.213.74.8
Jul89° / 78°2.28.613.64.5
Aug89° / 78°2.39.7134.2
Sep87° / 75°4.313.812.24.5
Oct81° / 67°3.48.811.36.8
Nov73° / 59°2.26.810.67.4
Dec67° / 52°2.16.310.36.7

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 47% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 15% of September, with mostly cloudy or overcast conditions the remaining 38%. Skies tend to open up as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
15743
25743
35743
45644
55743
65644
75644
85743
95743
105743
115743
125842
135842
145941
156040
166040
176139
186238
196337
206436
216634
226733
236832
246931
257030
267129
277228
287327
297327
307327

Chance of precipitation in September

Any precipitation

Portland gets around 4.3 in of rain over 13.8 wet days in September, the wettest month. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 45% and peaks near 53% on the wettest days. The odds ease toward the end of the month.

0%20%40%60%151015202530
Rain chance (%)
150
251
351
452
553
653
753
853
953
1052
1152
1251
1351
1450
1549
1648
1747
1846
1944
2043
2141
2240
2338
2437
2535
2634
2733
2832
2931
3031

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

Most of September feels miserable — the stacked bands show each day's mix of comfort levels, read off the dew point.

By dew point, September lands in the miserable band about 47% of days. Sticky, muggy-or-worse air turns up on roughly 90% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)Miserable (%)
100143065
200153163
300153262
400153361
501153360
601253458
701263556
801263556
901263556
1001273555
1101373554
1201383553
1301383553
1402493451
15024103450
16124103449
17125113447
18135123446
19136123344
20237133243
21248143241
22248153139
23259153138
243510163036
253511163034
263612173032
273612173130
284613183129
294714183127
304714183125

Wind in September

Winds average 9 mph in September, the calmest month.

Across September, daily wind ranges from about 9 mph on the calmest days to 9 mph at its breeziest. It stays fairly steady from day to day.

051015151015202530
Wind speed (mph)Feels
19light breeze
29light breeze
39light breeze
49light breeze
59light breeze
69light breeze
79light breeze
89light breeze
99light breeze
109light breeze
119light breeze
129light breeze
139light breeze
149light breeze
159light breeze
169light breeze
179light breeze
189light breeze
199light breeze
209light breeze
219light breeze
229light breeze
239light breeze
249light breeze
259light breeze
269light breeze
279light breeze
289light breeze
299light breeze
309light breeze

Sunrise & sunset in September

DaylightNight

Daylight runs from about 12 h 36 min at the start of September to 11 h 48 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 48 minutes over September. Sunrise moves from 6:12 AM to 6:26 AM, and sunset from 6:46 PM to 6:12 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.66:126:46
212.66:126:45
312.56:126:44
412.56:136:43
512.56:136:42
612.46:146:41
712.46:146:39
812.46:156:38
912.46:156:37
1012.36:166:36
1112.36:166:35
1212.36:176:33
1312.26:176:32
1412.26:186:31
1512.26:186:30
1612.26:196:29
1712.16:196:27
1812.16:206:26
1912.16:206:25
2012.06:216:24
2112.06:216:22
2212.06:226:21
2312.06:226:20
2411.96:236:19
2511.96:236:18
2611.96:246:16
2711.96:246:15
2811.86:256:14
2911.86:256:13
3011.86:266:12

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 5.14 kWh/m².

For context, solar energy here swings from a low near 2.76 kWh/m² to a high of 6.6 kWh/m² in July across the year — September's 5.14 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
15.5Bright
25.5Bright
35.4Bright
45.4Bright
55.4Bright
65.3Bright
75.3Bright
85.3Bright
95.2Bright
105.2Bright
115.2Bright
125.1Bright
135.1Bright
145.1Bright
155.1Bright
165.1Bright
175.1Bright
185.0Bright
195.0Bright
205.0Bright
215.0Bright
225.0Bright
235.0Bright
245.0Bright
255.0Bright
265.0Bright
275.0Bright
285.0Bright
295.0Bright
305.0Bright
Planning a trip in September

Hazard calendar for Portland

In seasonPeak

In September, Portland sits inside its atlantic hurricane season. The full year is below, with each hazard's peak months called out.

Portland sits in the Atlantic hurricane belt; the season peaks August–October.

Atlantic hurricane
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

Is September a good time to visit Portland?

Our two travel scores rate September for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).

4.5
Sightseeing
10th-best month of the year
6.4
Beach & pool
7th-best month of the year

September is a reasonable time to visit Portland for sightseeing. The water and warmth also suit a beach or pool day.

What to pack for Portland in September

From September's temperature range, rain chance, sun and wind — what's worth putting in the bag.

In September, Portland sees daytime highs around 87°F and nights near 75°F. Pack light clothes and rain gear. Worth having: sun protection. About 14 days see rain.

light clothesrain gearsun protection

Sea temperature near Portland in September

The nearest coast averages about 84°F in September — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea at the nearest coast (about 21 mi away) is warmest in September at about 84°F and coldest in February near 64°F.

It's comfortable for a long swim from Mar 29 to Dec 20 — about 8.8 months when the water holds above 68°F.

60°70°80°90°JanFebMarAprMayJunJulAugSepOctNovDeccoolrefreshingwarmtropicalcomfortable to swim
Sea temperature (°F)Comfort
Jan65Cool
Feb64Cool
Mar66Cool
Apr71Refreshing
May77Warm
Jun82Tropical
Jul83Tropical
Aug84Tropical
Sep84Tropical
Oct80Warm
Nov73Refreshing
Dec69Refreshing

UV index in Portland in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 10 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Portland peaks around June 16 at about 11 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 21 at about 4 (moderate).

The index reaches 3 or more — the level where the WHO recommends sun protection — every month of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highExtremeVery highHighModerateJun 16UV 11Dec 21UV 4
UV index (midday)Level
Jan5Moderate
Feb6High
Mar7High
Apr10Very high
May11Extreme
Jun11Extreme
Jul11Extreme
Aug11Extreme
Sep10Very high
Oct7High
Nov5High
Dec4Moderate

Air quality in Portland in September

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where September falls, not just the annual average.

Air quality in Portland is worst in July — around 20 µg/m³ PM2.5 (moderate), about 3.2× the cleanest month (November, 6 µg/m³).

Modeled monthly averages (CAMS reanalysis, 2015–2024).

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodJul 1419 µg/m³Nov 116 µg/m³
PM2.5 (µg/m³)Level
Jan8Good
Feb9Good
Mar12Good
Apr12Good
May16Moderate
Jun17Moderate
Jul20Moderate
Aug13Moderate
Sep11Good
Oct6Good
Nov6Good
Dec7Good
Location & terrain

Where is Portland?

Portland sits at 27.9°N, 97.3°W, 43 ft above sea level, in United States. The nearest listed city is Corpus Christi, 6.8 mi away.

Topography around Portland

How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of Portland.

Within 2 miles, the terrain around Portland has only modest variations in elevation — a maximum elevation change of 56 ft around an average of 16 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 115 ft; within 50 miles, only modest variations in elevation — a maximum elevation change of 394 ft.

The land around Portland is covered by water (47%) and artificial surfaces (25%) within 2 miles, water (38%) and cropland (33%) within 10 miles, and water (33%), grassland (23%) and cropland (20%) within 50 miles.

2 miles
56 ft
10 miles
115 ft
50 miles
394 ft
treesgrasslandcroplandartificial surfacesbare terrainwaterwetland
September weather nearby: Corpus Christi 6.8 mi · Kingsville 41 mi · Alice 47 mi · Victoria 67 mi · Bay City 112 mi · Harlingen 119 mi · Edinburg 121 mi · San Benito 122 mi

United States travel facts

Power plugs
Type A / B
120 V · 60 Hz
Prices
≈ 100% of US
price level, 2025
GDP per capita
$90,027
2025
Happiness
6.8 / 10
World Happiness, 2025
Safe drinking water
98%
of population, 2024
Homicide rate
5.8
per 100k, 2023
Road deaths
12.7
per 100k/yr, 2019
Income group
High
World Bank
Religion
Protestant 47%unaffiliated 23%Roman Catholic 21%Jewish 2%

Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.

Data sources

Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Portland (27.8773°, -97.3239°, elevation 43 ft), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google. Tropical-cyclone seasons are the published climatological basin seasons (NOAA National Hurricane Center / regional warning centres). Sea temperatures are the NOAA OISST v2.1 1991–2020 monthly climatology (public domain), sampled at the nearest ocean point. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Monthly air-quality (PM2.5) seasonality is from the CAMS EAC4 reanalysis (Copernicus Atmosphere Monitoring Service), scaled to the WHO annual mean where available. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).