Seattle weather in September (Washington State, United States of America)

What can you expect from the weather in Seattle during September? Wondering if it's an optimal time for a visit? This page provides detailed information on the weather conditions for that month.

In Seattle the weather in September is generally perfect, characterized by pleasant temperatures and moderate rainfall. September is a summer month. Anticipate daytime temperatures around 22°C, while night temperatures can drop to 12°C.

Seattle in September usually receives moderate rainfall, averaging around 49 mm for the month. Based on our climate data of the past 30 years, about 9 days of rain are anticipated.

The city usually sees around 220 hours of sunlight, indicating many sunny days.

If you're a fan of comfortable temperatures and drier conditions, September is a great time to visit. June, July, August and September generally stand out with the best circumstances. While January, February, March, November and December tend to showcase less optimal conditions.

For an in-depth look at the yearly conditions, visit our specialized Seattle climate page with graphs.

 

Seattle, monthly averages in September

Min TemperatureMin Temperature 12°C  
Max TemperatureMax Temperature 22°C  
Chance of RainChance of Rain 31%  
PrecipitationPrecipitation 49 mm  
Rainy daysRainy days 9 days  
HumidityHumidity 73%  
WindspeedWindspeed 14 km/h  
SunshineSunshine 220 hours  
Percentage SunshinePercentage Sunshine 59%  

Where to go in the United States of America in September

Find out more about the weather in the United States of America in September and which places have the best weather conditions in this month.

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Legend perfect weather pleasant tolerable unpleasant poor
Perfect weather is subjective. On this map perfect weather has been defined with temperatures between 20°C and 29°C and not too much precipitation (less than 90 mm a month).

So, what should you wear in Seattle in September?

For visitors traveling to Seattle, we recommend wearing layers. So maybe a skirt, t-shirt, shorts for during the day and jeans and a warm jacket for some days and evenings. Bring a rain jacket in case it rains during your stay. Plan on layering your clothes.

What To Do

We rated the following activities from 1 (least suitable) to 10 (best) to do in September.

Cycling
10/10
Walking
10/10
Barbeque
9/10
Camping
10/10
Outdoor sports
10/10

Interested in more climate information?

Weather and Climate provides you with all the information you need about the climate in Seattle.

Our site offers climate and forecast data for every country in the world. Are you going to the United States of America? On this website you can find historical weather averages for many cities in the United States of America. Not sure yet where to go? We now have a tool which recommends destinations that suit your ideal climate conditions. Find out where to go with our weather planner.