September weather forecast
Terrace Heights, WA

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Weather in September

The first month of the autumn, September, is still a warm month in Terrace Heights, Washington, with an average temperature fluctuating between 74.8°F (23.8°C) and 53.4°F (11.9°C).

Temperature

With September's onset, the average high-temperature recedes from August's tropical 86.5°F (30.3°C) to a warm 74.8°F (23.8°C). September is noted for a mean low-temperature of 53.4°F (11.9°C).

Humidity

In Terrace Heights, the average relative humidity in September is 48%.

Rainfall

In Terrace Heights, in September, it is raining for 3.9 days, with typically 0.24" (6mm) of accumulated precipitation. In Terrace Heights, during the entire year, the rain falls for 82.2 days and collects up to 5.43" (138mm) of precipitation.

Snowfall

Months with snowfall are January through March, September, November and December. September is the first month it typically snows. Throughout September, in the average 0.1 snowfall days, it receives 0.04" (1mm) of snow. Throughout the year, there are 18.5 snowfall days, and 7.8" (198mm) of snow is accumulated.

Daylight

In September, the average length of the day is 12h and 32min.
On the first day of September in Terrace Heights, sunrise is at 6:22 am and sunset at 7:40 pm. On the last day of the month, sunrise is at 7:00 am and sunset at 6:42 pm PDT.

Sunshine

The average sunshine in September is 11.1h.

UV index

The average daily maximum UV index in September is 4. A UV Index reading of 3 to 5 represents a moderate threat to health from exposure to the Sun's UV radiation for the ordinary person.
Note: A maximum UV index of 4 in September translates into the following recommendations:
Take precautions. Light skin individuals may get burned in less than 30 minutes. Solar radiation peaks around mid-day, so it's wise to limit exposure to the Sun at this time. Fend off the sun's harsh rays with appropriate clothing, a wide-brim hat, and UV-protective sunglasses. Attention! Nearly twice the Sun's UV radiation can be reflected by snow.
Updated: Aug 13, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What is the average September temperature?

An average high-temperature, in September, in Terrace Heights, is 74.8°F (23.8°C) and the average low-temperature is 53.4°F (11.9°C).

What is the average humidity in September?

In September, the average relative humidity is 48%.

How many days does it rain in September?

In Terrace Heights, in September, it is raining for 3.9 days, with typically 0.24" (6mm) of accumulated precipitation.

When does it start snowing?

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

How many hours of daylight does Terrace Heights have in September?

The average day length in September is 12h and 32min.

When is the sunrise / sunset in September?

On the first day of September, sunrise is at 6:22 am and sunset at 7:40 pm. On the last day of the month, sunrise is at 7:00 am and sunset at 6:42 pm PDT.

How long on average sun shines in September?

The average sunshine duration in September is 11.1h.

How high is the UV index in September?

In Terrace Heights, Washington, 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 unprotected exposure to UV radiation.
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
Terrace Heights, WA

Average temperature in September - Terrace Heights, WA
  • Average high temperature in September: 74.8°F

The warmest month (with the highest average high temperature) is August (86.5°F).
The month with the lowest average high temperature is December (36.9°F).

  • Average low temperature in September: 53.4°F

The month with the highest average low temperature is August (60.3°F).
The coldest month (with the lowest average low temperature) is December (25.5°F).

Average pressure in September
Terrace Heights, WA

Average pressure in September - Terrace Heights, WA
  • Average pressure in September: 29.97"Hg

The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is August (29.93"Hg).

Average wind speed in September
Terrace Heights, WA

Average wind speed in September - Terrace Heights, WA
  • Average wind speed in September: 6mph

The windiest month (with the highest average wind speed) is June (7.1mph).
The calmest month (with the lowest average wind speed) is December (4.4mph).

Average humidity in September
Terrace Heights, WA

Average humidity in September - Terrace Heights, WA
  • Average humidity in September: 48%

The month with the highest relative humidity is January (81%).
The months with the lowest relative humidity are July and August (39%).

Average rainfall in September
Terrace Heights, WA

Average rainfall in September - Terrace Heights, WA
  • Average rainfall in September: 0.24"

The wettest month (with the highest rainfall) is January (0.87").
The driest month (with the least rainfall) is July (0.08").

Average rainfall days in September
Terrace Heights, WA

Average rainfall days in September - Terrace Heights, WA
  • Average rainfall days in September: 3.9 days

The month with the highest number of rainy days is March (10.8 days).
The month with the least rainy days is August (2 days).

Average snowfall in September
Terrace Heights, WA

Average snowfall in September - Terrace Heights, WA
  • Average snowfall in September: 0.04"

The month with the highest snowfall is December (2.76").
The months with the least snowfall are April, May, June, July, August and October (0").

Average snowfall days in September
Terrace Heights, WA

Average snowfall days in September - Terrace Heights, WA
  • Average snowfall days in September: 0.1 days

The month with the highest number of snowfall days is December (5.4 days).
The months with the least snowfall days are May, June, July, August and October (0 days).

Average daylight in September /
Average sunshine in September
Terrace Heights, WA

Average daylight in September / Average sunshine in September - Terrace Heights, 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: 11h and 1min

The months with the most sunshine are July and August (Average sunshine: 12h and 6min).
The month with the least sunshine is January (Average sunshine: 5h and 36min).

Average sunshine days in September
Terrace Heights, WA

Average sunshine days in September - Terrace Heights, WA
  • Average sunshine days in September: 23.8 days

The month with the most sunshine days is July (27.5 days).
The month with the least sunshine days is February (15.8 days).

Average UV index in September
Terrace Heights, WA

Average UV index in September - Terrace Heights, WA
  • Average UV index in September: 4

The month with the highest UV index is July (UV index 7).
The months with the lowest UV index are January, February, November and December (UV index 2).

Average cloud cover in September
Terrace Heights, WA

Average cloud cover in September - Terrace Heights, WA
  • Average cloud cover in September: 14

The month with the most cloud cover is January (Cloud cover 40).
The months with the least cloud cover are July and August (Cloud cover 9).

Average visibility in September
Terrace Heights, WA

Average visibility in September - Terrace Heights, WA
  • Average visibility in September: 6mi

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

Terrace Heights, Washington, USA

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