Seattle Weather in September: Temperature, Precipitation, Wind

Updated on: June 22, 2024 Author: Rickey Bohn

Temperature

16.2°C

61.2°F

High temperature

20.9°C

69.6°F

Low temperature

12.4°C

54.4°F

Rainy days

11 days

Rainfall level

2.38mm

0.09 inch

Cloud coverage

52.1%

Wind speed

15.2km/h

9.4mph

Daylight time

12:33:25

UV index

5.8

19.3°C

67.0°F

21.8°C

71.0°F

18.3°C

65.0°F

15.2°C

59.0°F

16.1°C

61.0°F

17.5°C

64.0°F

17.2°C

63.0°F

17.0°C

63.0°F

18.6°C

65.0°F

19.8°C

68.0°F

18.4°C

65.0°F

16.3°C

61.0°F

17.8°C

64.0°F

18.2°C

65.0°F

19.4°C

67.0°F

18.2°C

65.0°F

16.7°C

62.0°F

15.8°C

60.0°F

15.2°C

59.0°F

13.8°C

57.0°F

13.9°C

57.0°F

16.3°C

61.0°F

14.8°C

59.0°F

13.9°C

57.0°F

14.7°C

58.0°F

13.0°C

55.0°F

13.2°C

56.0°F

12.6°C

55.0°F

11.5°C

53.0°F

12.1°C

54.0°F

In September, Seattle has an average temperature of 16.2°C (61.2°F), with highs of 20.9°C (69.6°F) and lows of 12.4°C (54.4°F). It feels slightly cooler than the actual temperatures, with an average feel-like temperature of 16.2°C (61.2°F).

Detailed weather report for Seattle in September

Seattle experiences moderate humidity in September, with an average of 71.8%. There is an average of 36.7% chance of precipitation, with a higher chance of 11.8% that it will result in measurable rainfall. Seattle receives an average of 2.38 inches of precipitation throughout the month, with 11 days having some form of rainfall. Winds in Seattle have an average speed of 15.2 km/h (9.4 mph), with gusts reaching 26.7 km/h (16.6 mph). The average atmospheric pressure is 1016.2 mb (29.99 inHg). Seattle has an average cloud cover of 52.1% in September, with visibility at 15.4 miles. The average UV index is 5.8, which represents a moderate risk of harm from unprotected sun exposure.

What is the temperature in Seattle in September?

Average air temperature in Seattle is 16.2°C (61.2°F) in September. The outside temperature in Seattle feels like 16.2°C (61.2°F) on a typical September day. The highest average temperature during sunny days is 20.9°C (69.6°F) and feels like 20.8°C (69.5°F). The lowest average temperature after dark is 12.4°C (54.4°F) which feels like 12.3°C (54.2°F).

How hot is Seattle in September?

The hot temperature in September in Seattle rises to 29.1°C (84.4°F) on sunny days with low cloud coverage and 71.8% humidity. During hottest days of September it feels like 28.3 °C (82.9°F). The average maximum temp in Seattle is 20.9°C (82.9°F) during day time in September.

How cold is Seattle in September?

The coldest temp in Seattle in September drops to 8.2°C (46.8°F) during the cold nights. With 15.2km/h (9.4mph) winds and 71.8% humidity it feels like 7.3°C (45.1°F) on the coldest nights. The average minimum temperature is 12.4°C (54.4°F) during night time in September.

Does it rain in Seattle in September?

Yes, it rains for 11 days in Seattle, United States in September averaging 2.38 mm of precipitation. Seattle has a 36.7% chance for rain throughout the entire month of September.

How much does it rain in Seattle throughout September?

Seattle has 2.38 mm (0.09 inch) of rain per day on average in September. It rains for an average of 11 days out of the entire month.

Is Seattle windy in September?

The average speed of wind in Seattle, United States during September is 15.2km/h (9.4mph) and average windgust is 26.7km/h (16.6mph). On some days in September wind can reach up to 22.4km/h (13.9mph).

What is the direction of the wind in Seattle in September?

Most days of September the wind is blowing from Southwest direction in Seattle.

What are the humidity levels in Seattle in September?

The average humidity levels in Seattle in September are 71.8%. Daily humidity levels in Seattle range from 59.5% to 89.3% during September.

How many hours of daylight are in Seattle in September?

Seattle has 12 hours 33 minutes of daylight in September on average. Sunset and sunrise times gradually change throughout the month. Sunrise in Seattle in September is at 6:47:12 and the sunset is at 19:20:38.

What is the cloud coverage in Seattle in September?

Clouds cover 52.1% of the sky on average throughout September in Seattle. The cloud coverage ranges from 0.3% to 99.1% depending on the day of the month.

What is the UV level in September in Seattle?

The average UV index in Seattle is 5.8 in September. UV levels change throughout the month and range from 1 to 8.

What is the solar radiation in Seattle in September?

The average solar radiation is 148.7 W/m2 (Watts per square meter) in Seattle during September. However solar radiation levels change throughout the month and range from 30.4 W/m2 to 237.5 W/m2.

What is the solar energy during September in Seattle?

The average solar energy during September in Seattle is 12.8 MJ/m2 (megajoules per square metre). Solar energy ranges from 2.6 MJ/m2, to 20.6 MJ/m2 during September.

Are there severe weather risks in Seattle in September?

Yes, there is a 10% risk for severe weather in Seattle, United States in September.

What is the air pressure in Seattle in September?

On average the air pressure in Seattle in September is 1016.2 mb (millibars). Throughout the month the sea level pressure ranges from 1008.6 mb to 1021.3 mb.

What is the visibility in Seattle in September?

The average daylight visibility in Seattle in September is 15.4 km (9.6 miles). Depending on the precipitation the visibility ranges from 13 km (8.1 miles) to 16 km (9.9 miles) throughout September.

What is the dew point in Seattle in September?

The average dew point in Seattle during September is 10.7°C (51.2°F).

Where is the data for Seattle climate in September coming from?

The climate data for Seattle, Washington, United States in September is collected from the following weather stations.

SEATTLE TACOMA AIRPORT, WA US
RENTON MUNICIPAL AIRPORT, WA US
SEATTLE BOEING FIELD, WA US
FW0821 Seattle WA US
KBFI
KRNT
KSEA