September weather forecast
Chinook, WA

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Weather in September

September, the first month of the autumn in Chinook, is still a refreshing month, with an average temperature varying between 62.6°F (17°C) and 55°F (12.8°C).

Temperature

During September, the average high-temperature is a still comfortable 62.6°F (17°C), maintaining a close resemblance to that of the preceding month. In Chinook, the nocturnal temperatures throughout September show a marginal dip from the daytime averages, settling at a cool 55°F (12.8°C).

Humidity

The average relative humidity in September is 83%.

Rainfall

In Chinook, during September, the rain falls for 9.9 days and regularly aggregates up to 0.94" (24mm) of precipitation. In Chinook, during the entire year, the rain falls for 165.1 days and collects up to 19.92" (506mm) of precipitation.

Snowfall

January, February and September are months with snowfall in Chinook, Washington. September is the first month it typically snows in Chinook. Throughout September, in the average 0.1 snowfall days, it receives 0.04" (1mm) of snow. Throughout the year, in Chinook, there are 1.8 snowfall days, and 0.47" (12mm) of snow is accumulated.

Daylight

The average length of the day in September in Chinook is 12h and 31min.
On the first day of the month, sunrise is at 6:37 am and sunset at 7:53 pm. On the last day of September, in Chinook, sunrise is at 7:14 am and sunset at 6:56 pm PDT.

Sunshine

In Chinook, the average sunshine in September is 8.7h.

UV index

May through September, with an average maximum UV index of 4, are months with the highest UV index. A UV Index estimate of 3 to 5 represents a moderate threat to health from unprotected exposure to Sun's UV rays for ordinary individuals.
Note: An average UV index of 4 in September transforms into this advice:
Undertake precautions - It is suggested to shield oneself from sunburn. Sun exposure should be minimized, especially during midday, to avoid harmful UV radiation. Clothes that are both tight-knit and comfortably loose are prime choices for sun protection. Be on the lookout! Nearly twofold UV radiation from the Sun can be reflected by snow.
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Frequently asked questions

What is the average September temperature in Chinook?

In September, the average high-temperature and low-temperature in Chinook are 62.6°F (17°C) and 55°F (12.8°C) respectively.

What is the average humidity in September in Chinook?

The average relative humidity in September in Chinook is 83%.

How much does it rain in Chinook in September?

In Chinook, Washington, in September, during 9.9 rainfall days, 0.94" (24mm) of precipitation is typically accumulated.

When does it start to snow in Chinook?

September is the first month it typically snows. Throughout September, in the average 0.1 snowfall days, it receives 0.04" (1mm) of snow.

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

The average day length in September is 12h and 31min.

When is the sunrise / sunset in September in Chinook?

In September, on the first day of the month, sunrise is at 6:37 am and sunset at 7:53 pm. On the last day of the month, in Chinook, Washington, sunrise is at 7:14 am and sunset at 6:56 pm PDT.

How many hours of sunshine does Chinook have in September?

In September, the average sunshine duration in Chinook, Washington, is 8.7h.

What are the months with the highest UV index in Chinook?

The months with the highest UV index in Chinook, Washington, are May through September, with an average maximum UV index of 4.

How high is the UV index in September in Chinook?

In September, the average daily maximum UV index in Chinook is 4. A UV Index of 3 to 5 symbolizes a moderate health threat from 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
Chinook, WA

Average temperature in September - Chinook, WA
  • Average high temperature in September: 62.6°F

The warmest month (with the highest average high temperature) is August (63.9°F).
The month with the lowest average high temperature is December (46.8°F).

  • Average low temperature in September: 55°F

The month with the highest average low temperature is August (55.9°F).
The coldest month (with the lowest average low temperature) is December (41.5°F).

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Average pressure in September
Chinook, WA

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

The month with the highest atmospheric pressure is July (30.08"Hg).
The month with the lowest atmospheric pressure is March (30.01"Hg).

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Average wind speed in September
Chinook, WA

Average wind speed in September - Chinook, WA
  • Average wind speed in September: 7.8mph

The windiest month (with the highest average wind speed) is January (11.9mph).
The calmest month (with the lowest average wind speed) is August (7.1mph).

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Average humidity in September
Chinook, WA

Average humidity in September - Chinook, WA
  • Average humidity in September: 83%

The month with the highest relative humidity is August (86%).
The month with the lowest relative humidity is April (80%).

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Average rainfall in September
Chinook, WA

Average rainfall in September - Chinook, WA
  • Average rainfall in September: 0.94"

The wettest month (with the highest rainfall) is December (3.31").
The driest month (with the least rainfall) is July (0.35").

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Average rainfall days in September
Chinook, WA

Average rainfall days in September - Chinook, WA
  • Average rainfall days in September: 9.9 days

The month with the highest number of rainy days is November (18.5 days).
The month with the least rainy days is August (6.7 days).

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Average snowfall in September
Chinook, WA

Average snowfall in September - Chinook, WA
  • Average snowfall in September: 0.04"

The month with the highest snowfall is February (0.31").
The months with the least snowfall are March, April, May, June, July, August, October, November and December (0").

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Average snowfall days in September
Chinook, WA

Average snowfall days in September - Chinook, WA
  • Average snowfall days in September: 0.1 days

The month with the highest number of snowfall days is February (0.8 days).
The months with the least snowfall days are April, May, June, July, August and October (0 days).

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Average daylight in September /
Average sunshine in September
Chinook, WA

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

The month with the longest days is June (Average daylight: 15h and 42min).
The month with the shortest days is December (Average daylight: 8h and 42min).

  • Average sunshine in September: 8h and 4min

The month with the most sunshine is July (Average sunshine: 9h and 42min).
The month with the least sunshine is January (Average sunshine: 3h and 48min).

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Average sunshine days in September
Chinook, WA

Average sunshine days in September - Chinook, WA
  • Average sunshine days in September: 17.1 days

The month with the most sunshine days is August (20.3 days).
The month with the least sunshine days is November (8.9 days).

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Average UV index in September
Chinook, WA

Average UV index in September - Chinook, WA
  • Average UV index in September: 4

The months with the highest UV index are May, June, July, August and September (UV index 4).
The months with the lowest UV index are February, November and December (UV index 2).

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Average cloud cover in September
Chinook, WA

Average cloud cover in September - Chinook, WA
  • Average cloud cover in September: 37

The month with the most cloud cover is January (Cloud cover 60).
The months with the least cloud cover are August and September (Cloud cover 37).

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Average visibility in September
Chinook, WA

Average visibility in September - Chinook, WA
  • Average visibility in September: 6mi

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

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Chinook, Washington, USA

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