Corvallis weather in September

In September, Corvallis sees average daytime highs of 76°F and overnight lows near 51°F, with 1.4 in of rain across 4.6 wet days and about 12.3 hours of daylight. It is the 3rd-warmest and 10th-wettest month of the year here.

Highs ease over the month, from about 79°F in the first days to 72°F by the end. The sky is clear or mostly clear about 53% of the time in September, and the air most often feels dry.

Daylight stretches from about 13 h 06 min at the start of September to 11 h 36 min by month's end. Set against the rest of the year, September is Corvallis's 3rd-clearest and 12th-windiest month. For the whole year in context, see Corvallis's year-round climate.

Daytime high
76°
3rd warmest
Overnight low
51°
10th coldest
Rainfall
1.4 in
4.6 wet days
Daylight
12 h 18 min
5:58 AM – 6:17 PM
Cloud cover
38%
3rd clearest
Wind
4 mph
12th windiest
Solar energy
4.73 kWh/m²
Travel score
8.0
out of 10

Corvallis is city in and county seat of Benton County, Oregon, United States.

Density
1,506/km²
people per km²
Founded
1845

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 79°F in the first days to 72°F by the end.

A typical September day in Corvallis reaches about 76°F in the afternoon and slips back to 51°F overnight — a 25°F spread between the day's warmth and the night's chill. On most days the high lands between 65°F and 87°F. Set against its neighbours, September runs about 6°F cooler than August and about 12°F warmer than October.

40°60°80°151015202530
Avg high (°F)Avg low (°F)
18053
27953
37953
47953
57953
67853
77852
87852
97852
107852
117752
127752
137752
147651
157651
167651
177551
187551
197550
207450
217450
227450
237450
247349
257349
267349
277249
287248
297148
307148

How September really feels in Corvallis

Once humidity and wind are folded in, September averages 0 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
0
heat index over the day's high
Days feeling ≤ 32°F
0
wind chill below the day's low

September sits comfortably in between — no days that feel dangerously hot or drop to a hard freeze once humidity and wind are folded in.

Corvallis weather by month

How September compares with the rest of the year at a glance. September is the 3rd-warmest and 10th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan47° / 36°6.916.91.791.3
Feb50° / 36°5.314.71.410.12.0
Mar55° / 38°6.016.80.911.62.8
Apr59° / 41°4.415.20.113.23.9
May66° / 46°2.810.3014.65.9
Jun72° / 50°1.46.3015.37.3
Jul81° / 55°0.31.80158.0
Aug82° / 55°0.42.2013.97.8
Sep76° / 51°1.44.6012.38.0
Oct64° / 44°3.810.7010.75.6
Nov52° / 39°6.816.50.29.42.3
Dec46° / 35°8.117.21.38.71.0

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 53% 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 32%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
17723
27624
37624
47426
57426
67327
77228
87129
97030
106832
116832
126733
136634
146535
156535
166535
176535
186535
196535
206535
216535
226535
236535
246535
256535
266436
276436
286337
296238
306238

Chance of precipitation in September

Any precipitation

Corvallis gets around 1.4 in of rain over 4.6 wet days in September. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 17% and peaks near 24% on the wettest days. The odds climb toward the end of the month.

0%10%20%30%151015202530
Rain chance (%)
110
210
310
411
511
611
712
812
913
1014
1115
1216
1316
1417
1517
1618
1718
1818
1919
2019
2119
2220
2320
2420
2521
2621
2722
2822
2923
3024

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, September lands in the dry band about 89% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)
187130
287130
387130
487130
587130
688120
788120
888120
988120
1088120
1188120
1288120
1388120
1488120
1588120
1688120
1788120
1888120
1988120
2089110
2189110
2289110
2390100
2489101
259091
269091
279181
289181
299271
309271

Wind in September

Winds average 4 mph in September, the calmest month.

Across September, daily wind ranges from about 4 mph on the calmest days to 4 mph at its breeziest. It stays fairly steady from day to day.

0246810151015202530
Wind speed (mph)Feels
14calm
24calm
34calm
44calm
54calm
64calm
74calm
84calm
94calm
104calm
114calm
124calm
134calm
144calm
154calm
164calm
174calm
184calm
194calm
204calm
214calm
224calm
234calm
244calm
254calm
264calm
274calm
284calm
294calm
304calm

Sunrise & sunset in September

DaylightNight

Daylight runs from about 13 h 06 min at the start of September to 11 h 36 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 90 minutes over September. Sunrise moves from 5:40 AM to 6:15 AM, and sunset from 6:45 PM to 5:49 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.15:406:45
213.05:416:44
313.05:436:42
412.95:446:40
512.95:456:38
612.85:466:36
712.85:476:34
812.75:496:32
912.75:506:30
1012.65:516:28
1112.65:526:26
1212.55:536:24
1312.55:556:22
1412.45:566:20
1512.45:576:18
1612.35:586:17
1712.35:596:15
1812.26:016:13
1912.16:026:11
2012.16:036:09
2112.06:046:07
2212.06:066:05
2311.96:076:03
2411.96:086:01
2511.86:095:59
2611.86:105:57
2711.76:125:55
2811.76:135:53
2911.66:145:51
3011.66:155:49

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.73 kWh/m².

For context, solar energy here swings from a low near 1.12 kWh/m² to a high of 7.2 kWh/m² in July across the year — September's 4.73 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
15.5Bright
25.5Bright
35.4Bright
45.4Bright
55.3Bright
65.3Bright
75.2Bright
85.1Bright
95.1Bright
105.0Bright
115.0Bright
124.9Bright
134.8Bright
144.8Bright
154.7Bright
164.6Bright
174.6Bright
184.5Bright
194.5Bright
204.4Bright
214.3Bright
224.3Bright
234.2Bright
244.2Bright
254.1Bright
264.1Bright
274.0Bright
283.9Moderate
293.9Moderate
303.8Moderate
Planning a trip in September

Hazard calendar for Corvallis

In seasonPeak

None of Corvallis's seasonal hazards are active in September. The full-year calendar below shows when the rainy season, cyclone risk and dust haze do peak.

Corvallis's rainy season runs October–April, when most of the year's rain falls.

Rainy season
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

Is September a good time to visit Corvallis?

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

8.0
Sightseeing
1st-best month of the year
6.7
Beach & pool
3rd-best month of the year

September is one of the better times to visit Corvallis for general sightseeing. The water and warmth also suit a beach or pool day.

What to pack for Corvallis in September

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

In September, Corvallis sees daytime highs around 76°F and nights near 51°F. Worth packing: light clothes and sun protection. About 5 days see rain.

light clothessun protection

Sea temperature near Corvallis in September

The nearest coast averages about 56°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 43 mi away) is warmest in July at about 56°F and coldest in February near 50°F.

The water stays below 68°F all year — cool enough that most swimmers want a wetsuit.

48°50°52°54°56°58°JanFebMarAprMayJunJulAugSepOctNovDecbracing
Sea temperature (°F)Comfort
Jan50Bracing
Feb50Bracing
Mar50Bracing
Apr51Bracing
May54Bracing
Jun56Bracing
Jul56Bracing
Aug56Bracing
Sep56Bracing
Oct55Bracing
Nov53Bracing
Dec51Bracing

UV index in Corvallis in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 5 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Corvallis peaks around July 16 at about 8 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 18 at about 1 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 8 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighVery highHighModerateLowJul 16UV 8Dec 18UV 1
UV index (midday)Level
Jan1Low
Feb2Low
Mar4Moderate
Apr5High
May8Very high
Jun7Very high
Jul8Very high
Aug7Very high
Sep5Moderate
Oct4Moderate
Nov1Low
Dec1Low

Air quality in Corvallis 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 Corvallis is worst in September — around 40 µg/m³ PM2.5 (poor), about 7.1× the cleanest month (January, 6 µg/m³).

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

010203040JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateModerateGoodSep 1537 µg/m³Jan 186 µg/m³
PM2.5 (µg/m³)Level
Jan6Good
Feb8Good
Mar10Good
Apr11Good
May11Good
Jun8Good
Jul8Good
Aug16Moderate
Sep40Poor
Oct11Good
Nov11Good
Dec9Good
Location & terrain

Where is Corvallis?

Corvallis sits at 44.6°N, 123.3°W, 233 ft above sea level, in United States. The nearest listed city is Albany, 9.3 mi away.

Topography around Corvallis

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

Within 2 miles, the terrain around Corvallis has only modest variations in elevation — a maximum elevation change of 262 ft around an average of 233 ft above sea level; within 10 miles, large variations in elevation — a maximum elevation change of 2,014 ft; within 50 miles, very significant variations in elevation — a maximum elevation change of 4,997 ft.

The land around Corvallis is covered by trees (42%) and artificial surfaces (26%) within 2 miles, trees (47%) and cropland (31%) within 10 miles, and trees (70%) within 50 miles.

2 miles
262 ft
10 miles
2,014 ft
50 miles
4,997 ft
treesgrasslandcroplandartificial surfacesbare terrainwater
September weather nearby: Albany 9.3 mi · Lebanon 17 mi · Dallas 25 mi · Salem 29 mi · Four Corners 29 mi · Keizer 32 mi · Hayesville 32 mi · Eugene 37 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 Corvallis (44.5646°, -123.262°, elevation 233 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. 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).