September weather forecast
Lake Oswego, OR

Weather in September

September, the first month of the autumn in Lake Oswego, is still a warm month, with an average temperature varying between 51.1°F (10.6°C) and 74.1°F (23.4°C).

Temperature

In September, the average high-temperature slightly decreases from a warm 81.7°F (27.6°C) in August to a still moderately hot 74.1°F (23.4°C). In Lake Oswego, the average low-temperature is 51.1°F (10.6°C).

Humidity

In Lake Oswego, the average relative humidity in September is 69%.

Rainfall

In Lake Oswego, it is raining for 10.4 days, with typically 1.69" (43mm) of accumulated precipitation. In Lake Oswego, during the entire year, the rain falls for 172.2 days and collects up to 31.3" (795mm) of precipitation.

Snowfall

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

Daylight

In September, the average length of the day in Lake Oswego is 12h and 31min.
On the first day of September in Lake Oswego, sunrise is at 6:32 am and sunset at 7:48 pm. On the last day of the month, sunrise is at 7:07 am and sunset at 6:53 pm PDT.

Sunshine

The average sunshine in September in Lake Oswego, Oregon, is 9.3h.

UV index

In September, the average daily maximum UV index is 4. A UV Index of 3 to 5 symbolizes a moderate threat to health from exposure to the Sun's UV radiation for ordinary individuals.
Note: In September, the average maximum UV index of 4 translate into the following recommendations:
Take precautions - Protection against sun damage is advised. The solar radiation is most powerful near the mid-day, so the exposure to the direct Sun should be reduced accordingly. Sun-protective clothing, a long-sleeved shirt and pants, a wide-brimmed hat, and UVA and UVB-blocking sunglasses are particularly helpful in blocking UV radiation's harmful effects.
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FAQ

What is the temperature in September in Lake Oswego?

The average high-temperature, in September, in Lake Oswego, Oregon, is 74.1°F (23.4°C), while the average low-temperature is 51.1°F (10.6°C). The average heat index (a.k.a. 'felt air temperature', 'feels like'), which combines air temperature and relative humidity, in August is appraised at 84.2°F (29°C).

What is the average humidity in September in Lake Oswego?

In September, the average relative humidity in Lake Oswego, Oregon, is 69%.

How much does it rain in Lake Oswego in September?

In Lake Oswego, Oregon, in September, it is raining for 10.4 days, with typically 1.69" (43mm) of accumulated precipitation.

When it does not snow in Lake Oswego?

In Lake Oswego, snow does not fall in April through October.

How many hours of daylight does Lake Oswego have in September?

In Lake Oswego, Oregon, the average day length in September is 12h and 31min.

When are sunrise and sunset in September in Lake Oswego?

On the first day of September in Lake Oswego, Oregon, sunrise is at 6:32 am and sunset at 7:48 pm. On the last day of the month, sunrise is at 7:07 am and sunset at 6:53 pm PDT.

How long on average sun shines in September in Lake Oswego?

In Lake Oswego, Oregon, the average sunshine duration in September is 9.3h.

What is the UV index reading in September in Lake Oswego?

In Lake Oswego, Oregon, the average daily maximum UV index in September is 4. A UV Index reading of 3 to 5 represents a medium hazard to health from exposure to Sun's UV rays.
Average humidity
Average rainfall days
Average snowfall
Average snowfall days
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
Lake Oswego, OR

Average temperature in September - Lake Oswego, OR
  • Average high temperature in September: 74.1°F

The warmest month (with the highest average high temperature) is August (81.7°F).
The month with the lowest average high temperature is December (44.4°F).

  • Average low temperature in September: 51.1°F

The month with the highest average low temperature is August (54.5°F).
The coldest month (with the lowest average low temperature) is December (34.7°F).

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Average pressure in September
Lake Oswego, OR

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

The month with the highest atmospheric pressure is January (30.12"Hg).
The month with the lowest atmospheric pressure is August (30"Hg).

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Average wind speed in September
Lake Oswego, OR

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

The windiest month (with the highest average wind speed) is January (6mph).
The calmest month (with the lowest average wind speed) is August (3.7mph).

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Average humidity in September
Lake Oswego, OR

Average humidity in September - Lake Oswego, OR
  • Average humidity in September: 69%

The month with the highest relative humidity is February (84%).
The month with the lowest relative humidity is August (63%).

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Average rainfall in September
Lake Oswego, OR

Average rainfall in September - Lake Oswego, OR
  • Average rainfall in September: 1.69"

The wettest month (with the highest rainfall) is December (4.57").
The driest month (with the least rainfall) is July (0.31").

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Average rainfall days in September
Lake Oswego, OR

Average rainfall days in September - Lake Oswego, OR
  • Average rainfall days in September: 10.4 days

The month with the highest number of rainy days is March (20.4 days).
The month with the least rainy days is July (4.8 days).

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Average snowfall in September
Lake Oswego, OR

Average snowfall in September - Lake Oswego, OR
  • Average snowfall in September: 0"

The month with the highest snowfall is March (1.46").
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
Lake Oswego, OR

Average snowfall days in September - Lake Oswego, OR
  • Average snowfall days in September: 0 days

The month with the highest number of snowfall days is February (2.3 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
Lake Oswego, OR

Average daylight in September / Average sunshine in September - Lake Oswego, OR
  • Average daylight in September: 12h and 31min

The month with the longest days is June (Average daylight: 15h and 37min).
The month with the shortest days is December (Average daylight: 8h and 47min).

  • Average sunshine in September: 9h and 18min

The month with the most sunshine is August (Average sunshine: 11h and 0min).
The month with the least sunshine is February (Average sunshine: 4h and 12min).

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Average sunshine days in September
Lake Oswego, OR

Average sunshine days in September - Lake Oswego, OR
  • Average sunshine days in September: 17.5 days

The month with the most sunshine days is July (23.9 days).
The month with the least sunshine days is February (8.3 days).

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Average UV index in September
Lake Oswego, OR

Average UV index in September - Lake Oswego, OR
  • Average UV index in September: 4

The month with the highest UV index is July (UV index 6).
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
Lake Oswego, OR

Average cloud cover in September - Lake Oswego, OR
  • Average cloud cover in September: 33

The month with the most cloud cover is February (Cloud cover 57).
The month with the least cloud cover is August (Cloud cover 22).

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Average visibility in September
Lake Oswego, OR

Average visibility in September - Lake Oswego, OR
  • Average visibility in September: 6mi

The months with the highest visibility are July, August, September and October (6mi).
The months with the lowest visibility are January, February, March, April, May, June, November and December (5mi).

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