September weather forecast
Chehalis, WA

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Weather in September

The first month of the autumn, September, is also an agreeable month in Chehalis, Washington, with temperature in the range of an average low of 46.9°F (8.3°C) and an average high of 70.3°F (21.3°C).

Temperature

September is marked by a subtle drop in average high-temperatures, transitioning from a warm 77.5°F (25.3°C) in August to a pleasant 70.3°F (21.3°C). Nightly average temperatures in September reveal a significant dip from daytime highs in Chehalis, registering a consistent a chilly 46.9°F (8.3°C).

Humidity

In September, the average relative humidity is 79%.

Rainfall

In Chehalis, in September, it is raining for 11.3 days, with typically 1.65" (42mm) of accumulated precipitation. Throughout the year, there are 185.5 rainfall days, and 36.1" (917mm) of precipitation is accumulated.

Snowfall

April through October are months without snowfall.

Daylight

The average length of the day in September in Chehalis, Washington, is 12h and 32min.
On the first day of the month, sunrise is at 6:32 am and sunset at 7:50 pm. On the last day of September, sunrise is at 7:10 am and sunset at 6:52 pm PDT.

Sunshine

In Chehalis, the average sunshine in September is 8.3h.

UV index

The average daily maximum UV index in September is 3. A UV Index value of 3 to 5 symbolizes a moderate threat to health from unprotected exposure to Sun's UV rays for the ordinary person.
Note: In September, the UV index of 3 transforms into the following advice:
Heed the precautions - Suggestions to avoid sunburn are made. Solar radiation peaks around mid-day, so it's wise to limit exposure to the Sun at this time. Select sunglasses that boast both UVA and UVB protection to limit the adverse effects of the sun on the eyes.
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Frequently asked questions

What is the average September temperature in Chehalis?

The average high-temperature, in September, in Chehalis, is 70.3°F (21.3°C), while the average low-temperature is 46.9°F (8.3°C).

What is the average humidity in September in Chehalis?

The average relative humidity in September is 79%.

How many days does it rain in September in Chehalis?

In Chehalis, Washington, during September, the rain falls for 11.3 days and regularly aggregates up to 1.65" (42mm) of precipitation.

When it does not snow in Chehalis?

April through October are months without snowfall in Chehalis.

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

In September, the average day length in Chehalis, Washington, is 12h and 32min.

When is the sunrise / sunset in September in Chehalis?

In September, on the first day of the month, sunrise is at 6:32 am and sunset at 7:50 pm. On the last day of the month, in Chehalis, Washington, sunrise is at 7:10 am and sunset at 6:52 pm PDT.

How many hours of sunshine does Chehalis have in September?

In Chehalis, Washington, the average sunshine duration in September is 8.3h.

What is the UV index intensity in September in Chehalis?

In September, the average daily maximum UV index is 3. A UV Index of 3 to 5 symbolizes a moderate health threat from unsafe exposure to Sun's UV rays.
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
Chehalis, WA

Average temperature in September - Chehalis, WA
  • Average high temperature in September: 70.3°F

The warmest month (with the highest average high temperature) is August (77.5°F).
The month with the lowest average high temperature is December (42.6°F).

  • Average low temperature in September: 46.9°F

The month with the highest average low temperature is August (50°F).
The coldest month (with the lowest average low temperature) is December (33.1°F).

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Average pressure in September
Chehalis, WA

Average pressure in September - Chehalis, WA
  • Average pressure in September: 30.02"Hg

The month with the highest atmospheric pressure is January (30.09"Hg).
The months with the lowest atmospheric pressure are March, August and September (30.02"Hg).

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Average wind speed in September
Chehalis, WA

Average wind speed in September - Chehalis, WA
  • Average wind speed in September: 3.6mph

The windiest months (with the highest average wind speed) are January, March and November (4.5mph).
The calmest month (with the lowest average wind speed) is September (3.6mph).

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Average humidity in September
Chehalis, WA

Average humidity in September - Chehalis, WA
  • Average humidity in September: 79%

The months with the highest relative humidity are January, February, November and December (89%).
The month with the lowest relative humidity is July (73%).

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Average rainfall in September
Chehalis, WA

Average rainfall in September - Chehalis, WA
  • Average rainfall in September: 1.65"

The wettest month (with the highest rainfall) is January (5.51").
The driest month (with the least rainfall) is July (0.47").

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Average rainfall days in September
Chehalis, WA

Average rainfall days in September - Chehalis, WA
  • Average rainfall days in September: 11.3 days

The month with the highest number of rainy days is March (21.5 days).
The month with the least rainy days is August (6.4 days).

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Average snowfall in September
Chehalis, WA

Average snowfall in September - Chehalis, WA
  • Average snowfall in September: 0"

The month with the highest snowfall is February (1.93").
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
Chehalis, WA

Average snowfall days in September - Chehalis, WA
  • Average snowfall days in September: 0 days

The month with the highest number of snowfall days is February (3.5 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
Chehalis, WA

Average daylight in September / Average sunshine in September - Chehalis, WA
  • Average daylight in September: 12h and 3min

The month with the longest days is June (Average daylight: 15h and 48min).
The month with the shortest days is December (Average daylight: 8h and 36min).

  • Average sunshine in September: 8h and 2min

The month with the most sunshine is August (Average sunshine: 10h and 12min).
The month with the least sunshine is December (Average sunshine: 3h and 30min).

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Average sunshine days in September
Chehalis, WA

Average sunshine days in September - Chehalis, WA
  • Average sunshine days in September: 16.9 days

The months with the most sunshine days are July and August (20.8 days).
The month with the least sunshine days is February (7.6 days).

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Average UV index in September
Chehalis, WA

Average UV index in September - Chehalis, WA
  • Average UV index in September: 3

The month with the highest UV index is July (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
Chehalis, WA

Average cloud cover in September - Chehalis, WA
  • Average cloud cover in September: 47

The months with the most cloud cover are January, February and December (Cloud cover 65).
The month with the least cloud cover is August (Cloud cover 38).

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Average visibility in September
Chehalis, WA

Average visibility in September - Chehalis, WA
  • Average visibility in September: 4mi

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

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Chehalis, Washington, USA

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