September weather forecast and climate
Olympia, WA

The calm Capitol Lake overlooking the Washington State Capitol building in Olympia, Washington
The calm Capitol Lake overlooking the Washington State Capitol building in Olympia, Washington
September, the first month of the autumn, in Olympia, is also an agreeable month, with average temperature ranging between min 47.7°F (8.7°C) and max 70.5°F (21.4°C).

Temperature

In September, the average high-temperature marginally drops, from a warm 78.6°F (25.9°C) in August, to an agreeable 70.5°F (21.4°C). The average low-temperature, in Olympia, is 47.7°F (8.7°C).

Humidity

In Olympia, Washington, the average relative humidity is 78%.

Rainfall

In Olympia, during September, the rain falls for 11.7 days and regularly aggregates up to 1.81" (46mm) of precipitation. In Olympia, during the entire year, the rain falls for 177.4 days and collects up to 37.05" (941mm) of precipitation.

Snowfall

April through October are months without snowfall.

Daylight

The average length of the day is 12.5h.

Sunshine

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

UV index

In Olympia, the average daily maximum UV index is 4. A UV Index of 3 to 5 symbolizes a moderate threat to health from the exposure to the Sun's UV rays for ordinary individuals.
Note: The daily maximum UV index of 4 in September interpret into the following advice:
Take precautions - Protection against sun damage is advised. The solar radiation is most powerful near the mid-day, so the exposure to the direct Sun should be reduced accordingly. Sun-protective clothing, a long-sleeved shirt and pants, a wide-brimmed hat, and UVA and UVB-blocking sunglasses are particularly helpful in blocking UV radiation's harmful effects.

What is the temperature in September in Olympia?

The average high-temperature, in September, in Olympia, is 70.5°F (21.4°C), while the average low-temperature is 47.7°F (8.7°C).

What is the average humidity in September in Olympia?

In September, the average relative humidity in Olympia, Washington, is 78%.

How many days does it rain in September in Olympia?

In Olympia, in September, during 11.7 rainfall days, 1.81" (46mm) of precipitation is typically accumulated.

When it does not snow in Olympia?

In Olympia, Washington, snow does not fall in April through October.

How many hours of daylight does Olympia have in September?

In Olympia, the average length of the day in September is 12.5h.

How long on average sun shines in September in Olympia?

The average sunshine in September in Olympia, Washington, is 8.3h.

How high is the UV index in September in Olympia?

In Olympia, the average daily maximum UV index in September is 4. A UV Index of 3 to 5 symbolizes a medium hazard to health from unprotected exposure to the UV radiation.
Average temperature in September - Olympia, WA
  • Average high temperature in September: 70.5°F

The warmest month (with the highest average high temperature) is August (78.6°F).
The month with the lowest average high temperature is December (43°F).

  • Average low temperature in September: 47.7°F

The month with the highest average low temperature is August (50.5°F).
The coldest month (with the lowest average low temperature) is December (33.4°F).

Average pressure in September - Olympia, WA
  • Average pressure in September: 30.02"

The month with the highest atmospheric pressure is January (30.09").
The month with the lowest atmospheric pressure is March (30.01").

Average wind speed in September - Olympia, WA
  • Average wind speed in September: 3.8mph

The windiest months (with the highest average wind speed) are March and November (4.6mph).
The calmest month (with the lowest average wind speed) is September (3.8mph).

Average humidity in September - Olympia, WA
  • Average humidity in September: 78%

Months with the highest relative humidity are January, November and December (89%).
The month with the lowest relative humidity is July (71%).

Average rainfall in September - Olympia, WA
  • Average rainfall in September: 1.81"

The wettest month (with the highest rainfall) is December (5.79").
The driest month (with the least rainfall) is July (0.39").

Average rainfall days in September - Olympia, WA
  • Average rainfall days in September: 11.7 days

The month with the highest number of rainy days is March (20.4 days).
The month with the least rainy days is August (5.5 days).

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

The month with the highest snowfall is February (2.32").
Months with the least snowfall are April, May, June, July, August, September and October (0").

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

The month with the highest number of snowfall days is February (3.3 days).
Months with the least snowfall days are May, June, July, August, September and October (0 days).

Average daylight in September / Average sunshine in September - Olympia, WA
  • Average daylight in September: 12.5h

The month with the longest days is June (Average daylight: 15.8h).
The month with the shortest days is December (Average daylight: 8.6h).

  • Average sunshine in September: 8.3h

The month with the most sunshine is August (Average sunshine: 10.2h).
The month with the least sunshine is December (Average sunshine: 3.4h).

Average sunshine days in September - Olympia, WA
  • Average sunshine days in September: 16.1 days

The month with the most sunshine days is August (22.4 days).
The month with the least sunshine days is February (8.4 days).

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

Months with the highest UV index are June and July (UV index 5).
Months with the lowest UV index are January, February, November and December (UV index 2).

Average cloud cover in September - Olympia, WA
  • Average cloud cover in September: 45

Months with the most cloud cover are January and December (Cloud cover 65).
Months with the least cloud cover are July and August (Cloud cover 35).

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

Months with the highest visibility are June, July and August (5mi).
Months with the lowest visibility are January, February, March, April, May, September, October, November and December (4mi).