Weathermondo.com
United StatesThe weather in September in Seattle
It's pleasantly warm in September in Seattle with an average temperature of 22°C. Temperatures this month range from a low of 19°C to a high of 25°C. At night, you can expect temperatures between 12°C and 16°C.
Looking for great weather? September is a good time to be in Seattle. The temperatures are nice, and there’s not too much rain.
Average temperatures and precipitation
This chart shows the average daily maximum and minimum temperatures (in degrees Celsius) and precipitation (in millimeters) in September for Seattle, Washington. A low precipitation value usually indicates little to no rainfall on that day in recent years, while a higher value suggests more frequent rainfall.
Temperature records
With 32°C in 2020, Seattle reached the highest temperature in September over the past 10 years. The lowest daytime temperature in this month was 13°C in 2019. The extreme nighttime temperatures ranged from a lowest recorded value of 5°C to a highest value of 21°C.
Water temperature
The water temperature at Seattle is 16°C this month. This is probably too cold to swim without protective gear.
Rainfall amount
In September, there is an average of 34 mm of precipitation, spread over 6 days. The wind speed is around 3 Bft, mostly coming from the Southwest.
Daily weather in September for Seattle
Click on any day in September to get detailed info about the usual weather on that day in Seattle. Check out the historical temperatures and precipitation over the past 10 years on this day.
September weather comparison
| Seattle | New York | |
|---|---|---|
| Average temperature | 22°C | 27°C |
| Max. temperature | 25°C | 31°C |
| Min. temperature | 12°C | -5°C |
| Total precipitation | 34 mm | 57 mm |
| Rainy days | 6 days | 9 days |
Start of September
The month of September starts in Seattle with warm temps, averaging around 25°C during the day and nights around 15°C.
Mid September
By mid-September, daytime temps drop to around 22°C, with nights around 14°C. Not much precipitation expected during this period. It’s mostly dry and sunny.
End of September
By the end of September, the average daytime temperature in Seattle is around 21°C, while nighttime temps are about 13°C. A shower might pop up, but overall, the weather will be dry and sunny.
Find affordable trips to Seattle
UV index
The UV index is a maximum of 7 this month. That's a moderate to high value on the intensity scale of 1 to 11. Unprotected skin can burn within 15-25 minutes.
Check out the climate of Seattle for all months and discover the best travel time
Temperature charts
These charts show the average temperatures in September in Seattle, Washington. The temperatures are shown in degrees Celsius and are calculated based on data from the past 10 years.
Daily Temperature in September in Seattle
Temperature in September in Seattle over the years
Precipitation charts
These charts show the average amount of precipitation in September in Seattle, Washington. Precipitation is always measured as water, even when it falls as snow or hail The amount of precipitation is displayed in millimeters, while snowfall is shown in centimeters.
Daily Precipitation in September in Seattle
Total precipitation in September in Seattle over the years
Daily UV index in September in Seattle
This chart shows the average daily UV index in September in Seattle, with the UV index ranging from 0 to a maximum of 11. The bottom of the chart shows the days of the month. Based on historical data, this chart provides an idea of the daily UV radiation levels you can expect.
Weather experiences in September in Seattle
The weather in September in Seattle is rated 0 out of 5 stars by 1 visitor. Have you been to Seattle? Share your weather experience to help other visitors.
Have you been to Seattle in September?
Share your weather experience in September in Seattle.
Average weather in Seattle by month
Click on a month below to see detailed weather info for Seattle. Based on historical weather data, you can see the average temperature, precipitation, wind, and UV index for each day of the month.