September weather forecast
Twisp, WA

Weather in September

September, the first month of the autumn in Twisp, is still a comfortable month, with an average temperature varying between 65.3°F (18.5°C) and 42.1°F (5.6°C).

Temperature

In September, the average high-temperature decreases from a moderately hot 76.8°F (24.9°C) in August to an enjoyable 65.3°F (18.5°C). The average low-temperature, in September, is 42.1°F (5.6°C).

Humidity

The average relative humidity in September is 60%.

Rainfall

In Twisp, during 9.8 rainfall days, 0.94" (24mm) of precipitation is typically accumulated. Throughout the year, there are 141.4 rainfall days, and 18.07" (459mm) of precipitation is accumulated.

Snowfall

Months with snowfall are January through April, September through December. September is the first month it typically snows in Twisp. Throughout September, in the average 0.1 snowfall days, it receives 0.08" (2mm) of snow. Throughout the year, there are 64.4 snowfall days, and 42.6" (1082mm) of snow is accumulated.

Daylight

In September, the average length of the day in Twisp is 12h and 34min.
On the first day of September, sunrise is at 6:18 am and sunset at 7:42 pm. On the last day of the month, sunrise is at 6:58 am and sunset at 6:41 pm PDT.

Sunshine

In Twisp, the average sunshine in September is 10.7h.

UV index

In Twisp, the average daily maximum UV index in September is 3. A UV Index reading of 3 to 5 represents a moderate health risk from unprotected exposure to Sun's UV rays for average individuals.
Note: The average daily UV index of 3 in September transform into the following instructions:
Take precautions - Protection against sunburn is recommended. The solar radiation is most powerful near the mid-day, so the exposure to the direct Sun should be reduced accordingly. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes. Caution! The reflection of snow can nearly double the intensity of the Sun's UV radiation.
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FAQ

What is the average humidity in September in Twisp?

The average relative humidity in September in Twisp, Washington, is 60%.

How many days does it rain in September in Twisp?

In Twisp, Washington, in September, it is raining for 9.8 days, with typically 0.94" (24mm) of accumulated precipitation.

When does it start snowing in Twisp?

September is the first month it typically snows in Twisp. Throughout September, in the average 0.1 snowfall days, it receives 0.08" (2mm) of snow.

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

In Twisp, the average day length in September is 12h and 34min.

When are sunrise and sunset in September in Twisp?

In September, on the first day of the month, sunrise is at 6:18 am and sunset at 7:42 pm. On the last day of the month, in Twisp, Washington, sunrise is at 6:58 am and sunset at 6:41 pm PDT.

How many hours of sunshine does Twisp have in September?

The average sunshine duration in September in Twisp is 10.7h.

What is the UV index intensity in September in Twisp?

The average daily maximum UV index in September in Twisp, Washington, is 3. A UV Index estimate of 3 to 5 represents a medium health risk from exposure to the Sun's UV radiation.
Average humidity
Average rainfall days
Average snowfall
Average snowfall days
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
Twisp, WA

Average temperature in September - Twisp, WA
  • Average high temperature in September: 65.3°F

The warmest month (with the highest average high temperature) is August (76.8°F).
The month with the lowest average high temperature is December (27.9°F).

  • Average low temperature in September: 42.1°F

The month with the highest average low temperature is August (48.9°F).
The coldest month (with the lowest average low temperature) is December (14.7°F).

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Average pressure in September
Twisp, WA

Average pressure in September - Twisp, WA
  • Average pressure in September: 29.98"Hg

The month with the highest atmospheric pressure is January (30.15"Hg).
The month with the lowest atmospheric pressure is August (29.94"Hg).

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Average wind speed in September
Twisp, WA

Average wind speed in September - Twisp, WA
  • Average wind speed in September: 4.7mph

The windiest month (with the highest average wind speed) is July (5.1mph).
The calmest months (with the lowest average wind speed) are January and December (3.5mph).

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Average humidity in September
Twisp, WA

Average humidity in September - Twisp, WA
  • Average humidity in September: 60%

The months with the highest relative humidity are January and February (92%).
The months with the lowest relative humidity are July and August (51%).

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Average rainfall in September
Twisp, WA

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

The wettest month (with the highest rainfall) is December (2.52").
The driest month (with the least rainfall) is July (0.35").

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Average rainfall days in September
Twisp, WA

Average rainfall days in September - Twisp, WA
  • Average rainfall days in September: 9.8 days

The month with the highest number of rainy days is March (17.1 days).
The month with the least rainy days is August (5.7 days).

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Average snowfall in September
Twisp, WA

Average snowfall in September - Twisp, WA
  • Average snowfall in September: 0.08"

The month with the highest snowfall is December (12.28").
The months with the least snowfall are May, June, July and August (0").

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Average snowfall days in September
Twisp, WA

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

The month with the highest number of snowfall days is December (15.5 days).
The months with the least snowfall days are June, July and August (0 days).

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

Average daylight in September / Average sunshine in September - Twisp, WA
  • Average daylight in September: 12h and 34min

The month with the longest days is June (Average daylight: 16h and 2min).
The month with the shortest days is December (Average daylight: 8h and 24min).

  • Average sunshine in September: 10h and 42min

The months with the most sunshine are July and August (Average sunshine: 11h and 54min).
The month with the least sunshine is January (Average sunshine: 4h and 12min).

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Average sunshine days in September
Twisp, WA

Average sunshine days in September - Twisp, WA
  • Average sunshine days in September: 17.6 days

The month with the most sunshine days is August (22.8 days).
The month with the least sunshine days is March (8.9 days).

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Average UV index in September
Twisp, WA

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

The month with the highest UV index is July (UV index 6).
The months with the lowest UV index are January, February and November (UV index 1).

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Average cloud cover in September
Twisp, WA

Average cloud cover in September - Twisp, WA
  • Average cloud cover in September: 22

The month with the most cloud cover is January (Cloud cover 55).
The month with the least cloud cover is August (Cloud cover 14).

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Average visibility in September
Twisp, WA

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

The months with the highest visibility are April, May, June, July, August, September and October (6mi).
The month with the lowest visibility is January (3mi).

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