September weather forecast
Corvallis, OR

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A large river with two bridges across it in the city of Corvalis, Oregon, home to the famed Oregon State University
A large river with two bridges across it in the city of Corvalis, Oregon, home to the famed Oregon State University

Weather in September

September brings a salient shift in Corvallis, Oregon's weather as summer transitions into fall. Along with falling temperatures, daylight hours begin to shorten and more cloud coverage is observed. Mild rain returns, marking the beginning of the wetter part of the year. Temperature highs descend to 73.4°F (23°C) indicating the recession of summer's warmth. The mix of sunny and overcast days creates varied and picturesque sky vistas, popular for seasonal photography.

Temperature

Corvallis, Oregon, experiences a moderate temperature shift at the start of September, with average high-temperatures adjusting a bit from 80.4°F (26.9°C) in August to a still moderately hot 73.4°F (23°C). Corvallis, amid September nights, sees a noteworthy disparity from daily highs with an average temperature of 48.6°F (9.2°C).

Humidity

In September, the average relative humidity in Corvallis is 74%.

Rainfall

In Corvallis, during September, the rain falls for 9.3 days and regularly aggregates up to 1.42" (36mm) of precipitation. In Corvallis, during the entire year, the rain falls for 169.2 days and collects up to 30.28" (769mm) of precipitation.

Snowfall

In Corvallis, snow does not fall in April through October.

Daylight

In Corvallis, the average length of the day in September is 12h and 30min.
On the first day of the month, sunrise is at 6:36 am and sunset at 7:48 pm. On the last day of September, sunrise is at 7:10 am and sunset at 6:54 pm PDT.

Sunshine

In September, the average sunshine is 9h.

UV index

The average daily maximum UV index in September in Corvallis is 4. A UV Index reading of 3 to 5 represents a moderate health risk from unsafe exposure to UV radiation for the average person.
Note: During September, 4 as the daily maximum UV index converts into the following advice:
Take necessary precautions - Protection from skin and eye injury is mandatory. Solar radiation peaks around mid-day, so it's wise to limit exposure to the Sun at this time. Always opt for UVA and UVB-resistant sunglasses on radiant days.
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Frequently asked questions

What are September temperatures in Corvallis?

The high-temperature, in September, in Corvallis, is 73.4°F (23°C), while the low-temperature averages to 48.6°F (9.2°C).

What is the average humidity in September in Corvallis?

In Corvallis, Oregon, the average relative humidity in September is 74%.

How many days does it rain in September in Corvallis?

In September, the rain falls for 9.3 days. Throughout September, 1.42" (36mm) of precipitation is accumulated.

When it does not snow in Corvallis?

In Corvallis, Oregon, snow does not fall in April through October.

What is the average length of the day in September in Corvallis?

In Corvallis, Oregon, the average day length in September is 12h and 30min.

When are sunrise and sunset in September in Corvallis?

On the first day of September in Corvallis, sunrise is at 6:36 am and sunset at 7:48 pm. On the last day of the month, sunrise is at 7:10 am and sunset at 6:54 pm PDT.

How long on average sun shines in September in Corvallis?

In Corvallis, the average sunshine duration in September is 9h.

What is the UV index intensity in September in Corvallis?

The average daily maximum UV index in September is 4. A UV Index estimate of 3 to 5 represents a moderate vulnerability from unprotected exposure to UV radiation.
Average humidity
Average rainfall days
Average snowfall
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
Corvallis, OR

Average temperature in September - Corvallis, OR
  • Average high temperature in September: 73.4°F

The warmest month (with the highest average high temperature) is August (80.4°F).
The month with the lowest average high temperature is December (44.8°F).

  • Average low temperature in September: 48.6°F

The month with the highest average low temperature is August (52°F).
The coldest month (with the lowest average low temperature) is December (34.2°F).

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Average pressure in September
Corvallis, OR

Average pressure in September - Corvallis, OR
  • Average pressure in September: 30.01"Hg

The month with the highest atmospheric pressure is January (30.11"Hg).
The months with the lowest atmospheric pressure are August and September (30.01"Hg).

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Average wind speed in September
Corvallis, OR

Average wind speed in September - Corvallis, OR
  • Average wind speed in September: 3.9mph

The windiest month (with the highest average wind speed) is March (4.9mph).
The calmest month (with the lowest average wind speed) is September (3.9mph).

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Average humidity in September
Corvallis, OR

Average humidity in September - Corvallis, OR
  • Average humidity in September: 74%

The month with the highest relative humidity is December (89%).
The month with the lowest relative humidity is August (69%).

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Average rainfall in September
Corvallis, OR

Average rainfall in September - Corvallis, OR
  • Average rainfall in September: 1.42"

The wettest month (with the highest rainfall) is December (4.8").
The driest month (with the least rainfall) is July (0.28").

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Average rainfall days in September
Corvallis, OR

Average rainfall days in September - Corvallis, OR
  • Average rainfall days in September: 9.3 days

The month with the highest number of rainy days is March (20.9 days).
The month with the least rainy days is August (4.5 days).

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Average snowfall in September
Corvallis, OR

Average snowfall in September - Corvallis, OR
  • Average snowfall in September: 0"

The month with the highest snowfall is February (1.77").
The months with the least snowfall are April, May, June, July, August, September and October (0").

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Average snowfall days in September
Corvallis, OR

Average snowfall days in September - Corvallis, OR
  • Average snowfall days in September: 0 days

The month with the highest number of snowfall days is February (1.8 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).

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Average daylight in September /
Average sunshine in September
Corvallis, OR

Average daylight in September / Average sunshine in September - Corvallis, OR
  • Average daylight in September: 12h and 3min

The month with the longest days is June (Average daylight: 15h and 30min).
The month with the shortest days is December (Average daylight: 8h and 54min).

  • Average sunshine in September: 9h and 0min

The months with the most sunshine are July and August (Average sunshine: 10h and 48min).
The month with the least sunshine is February (Average sunshine: 3h and 36min).

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Average sunshine days in September
Corvallis, OR

Average sunshine days in September - Corvallis, OR
  • Average sunshine days in September: 19.3 days

The month with the most sunshine days is July (24.3 days).
The month with the least sunshine days is February (8.4 days).

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Average UV index in September
Corvallis, OR

Average UV index in September - Corvallis, OR
  • Average UV index in September: 4

The months with the highest UV index are June, July and August (UV index 5).
The months with the lowest UV index are January, February, November and December (UV index 2).

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Average cloud cover in September
Corvallis, OR

Average cloud cover in September - Corvallis, OR
  • Average cloud cover in September: 36

The month with the most cloud cover is February (Cloud cover 65).
The month with the least cloud cover is August (Cloud cover 25).

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Average visibility in September
Corvallis, OR

Average visibility in September - Corvallis, OR
  • Average visibility in September: 5mi

The months with the highest visibility are June, July, August, September and October (5mi).
The months with the lowest visibility are January, February, March, April, May, November and December (4mi).

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Corvallis, Oregon, USA

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