September weather forecast
Deer Park, WA

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Pine tree forests in the hilly region in the Olympic National Park in Deer Park, Washington
Pine tree forests in the hilly region in the Olympic National Park in Deer Park, Washington

Weather in September

The first month of the autumn, September, is also an agreeable month in Deer Park, Washington, with an average temperature fluctuating between 46.6°F (8.1°C) and 72.7°F (22.6°C).

Temperature

September ushers in a slight temperature change, with average high-temperatures reducing from August's moderately hot 84°F (28.9°C) to a pleasant 72.7°F (22.6°C). Deer Park's September nights cool down significantly from the day's heat, to an average low-temperature of 46.6°F (8.1°C).

Humidity

The average relative humidity in September is 53%.

Rainfall

In September, the rain falls for 7 days. Throughout September, 0.63" (16mm) of precipitation is accumulated. In Deer Park, during the entire year, the rain falls for 124.9 days and collects up to 17.44" (443mm) of precipitation.

Snowfall

Months with snowfall are January through May, September through December. September is the first month it typically snows. Throughout September, in the average 0.2 snowfall days, it receives 0.51" (13mm) of snow. Throughout the year, there are 69.2 snowfall days, and 42.99" (1092mm) of snow is accumulated.

Daylight

In Deer Park, the average length of the day in September is 12h and 33min.
On the first day of September, sunrise is at 6:09 am and sunset at 7:30 pm. On the last day of the month, sunrise is at 6:48 am and sunset at 6:30 pm PDT.

Sunshine

In September, the average sunshine in Deer Park is 10.1h.

UV index

The average daily maximum UV index in September in Deer Park is 4. A UV Index value of 3 to 5 symbolizes a moderate threat to health from exposure to the Sun's UV radiation for the ordinary person.
Note: The UV index of 4 in September translates into these instructions:
Put precautions into practice - Guidance to elude sunburn is provided. Midday Sun has the strongest UV rays, making it crucial to limit exposure and find shade. Select sunglasses that boast both UVA and UVB protection to limit the adverse effects of the sun on the eyes. Consider this! The reflection from snow can almost double the intensity of the Sun's UV radiation.

Frequently asked questions

What are the temperatures in September?

An average high-temperature, in September, in Deer Park, is 72.7°F (22.6°C) and the average low-temperature is 46.6°F (8.1°C). In August, the average heat index (a.k.a. 'felt air temperature', 'real feel'), which combines air temperature and relative humidity, is estimated at 84.2°F (29°C).

What is the average humidity in September?

In September, the average relative humidity is 53%.

How many days does it rain in September?

In September, the rain falls for 7 days. Throughout September, 0.63" (16mm) of precipitation is accumulated.

When does it start to snow?

September is the first month it typically snows. Throughout September, in the average 0.2 snowfall days, it receives 0.51" (13mm) of snow.

How many hours of daylight does Deer Park have in September?

In September, the average day length in Deer Park is 12h and 33min.

When is the sunrise / sunset in September?

In September, on the first day of the month, sunrise is at 6:09 am and sunset at 7:30 pm. On the last day of the month, sunrise is at 6:48 am and sunset at 6:30 pm PDT.

How many hours of sunshine does Deer Park have in September?

In September, the average sunshine duration is 10.1h.

What is the UV index reading in September?

The average daily maximum UV index in September in Deer Park is 4. A UV Index of 3 to 5 symbolizes a medium hazard to health from unsafe exposure to Sun's UV rays.
Average humidity
Average rainfall days
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
Deer Park, WA

Average temperature in September - Deer Park, WA
  • Average high temperature in September: 72.7°F

The warmest month (with the highest average high temperature) is August (84°F).
The month with the lowest average high temperature is December (31.3°F).

  • Average low temperature in September: 46.6°F

The month with the highest average low temperature is August (54.3°F).
The coldest month (with the lowest average low temperature) is December (20.3°F).

Average pressure in September
Deer Park, WA

Average pressure in September - Deer Park, WA
  • Average pressure in September: 29.96"Hg

The month with the highest atmospheric pressure is January (30.19"Hg).
The months with the lowest atmospheric pressure are June and August (29.91"Hg).

Average wind speed in September
Deer Park, WA

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

The windiest month (with the highest average wind speed) is April (5.6mph).
The calmest month (with the lowest average wind speed) is December (4mph).

Average humidity in September
Deer Park, WA

Average humidity in September - Deer Park, WA
  • Average humidity in September: 53%

The month with the highest relative humidity is January (92%).
The month with the lowest relative humidity is August (43%).

Average rainfall in September
Deer Park, WA

Average rainfall in September - Deer Park, WA
  • Average rainfall in September: 0.63"

The wettest month (with the highest rainfall) is January (2.4").
The driest month (with the least rainfall) is August (0.31").

Average rainfall days in September
Deer Park, WA

Average rainfall days in September - Deer Park, WA
  • Average rainfall days in September: 7 days

The month with the highest number of rainy days is March (16.2 days).
The month with the least rainy days is August (5.1 days).

Average snowfall in September
Deer Park, WA

Average snowfall in September - Deer Park, WA
  • Average snowfall in September: 0.51"

The month with the highest snowfall is January (13.23").
The months with the least snowfall are June, July and August (0").

Average snowfall days in September
Deer Park, WA

Average snowfall days in September - Deer Park, WA
  • Average snowfall days in September: 0.2 days

The month with the highest number of snowfall days is December (16.9 days).
The months with the least snowfall days are June, July and August (0 days).

Average daylight in September /
Average sunshine in September
Deer Park, WA

Average daylight in September / Average sunshine in September - Deer Park, WA
  • Average daylight in September: 12h and 4min

The month with the longest days is June (Average daylight: 16h and 0min).
The month with the shortest days is December (Average daylight: 8h and 30min).

  • Average sunshine in September: 10h and 1min

The month with the most sunshine is August (Average sunshine: 12h and 0min).
The month with the least sunshine is January (Average sunshine: 3h and 24min).

Average sunshine days in September
Deer Park, WA

Average sunshine days in September - Deer Park, WA
  • Average sunshine days in September: 21.3 days

The month with the most sunshine days is July (24.2 days).
The month with the least sunshine days is March (9.7 days).

Average UV index in September
Deer Park, WA

Average UV index in September - Deer Park, WA
  • 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 February, November and December (UV index 1).

Average cloud cover in September
Deer Park, WA

Average cloud cover in September - Deer Park, WA
  • Average cloud cover in September: 22

The month with the most cloud cover is January (Cloud cover 64).
The month with the least cloud cover is August (Cloud cover 13).

Average visibility in September
Deer Park, WA

Average visibility in September - Deer Park, 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).

Deer Park, Washington, USA

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