Weather in Seattle in September 2024
Average weather
Average temperature in Seattle in September
Going from a maximum of +32°C during the day to a minimum of +11°C during the night, the temperature in September averages around +24°C.
The average maximum temperature goes down 38% by the end of the month, compared with the beginning of the month, from +29°C to +21°C.
Is Seattle warm or cold in September?
Seattle is typically mild in September.
Maximum temperatures go down compared to the previous month from +24°C to +21°C. The minimum temperature also goes down from +14°C to +12°C.
Pack a light jacket as it will be warm in the day and cool in the evenings.
September is one of the warmest months in Seattle, here is the comparison with other months:
Climate in Seattle in September
| August | September | October | ||||
|---|---|---|---|---|---|---|
| Avg. temperature | ||||||
| +24°C | +21°C | +15°C | ||||
| Min. temperature | ||||||
| +8°C | +5°C | 0°C | ||||
| Max. temperature | ||||||
| +36°C | +33°C | +29°C | ||||
| Rainfall | ||||||
| 28 mm | 60 mm | 114 mm | ||||
| Wind | ||||||
| 1 m/s | 1 m/s | 1 m/s | ||||
| Humidity | ||||||
| 71% | 76% | 82% | ||||
| Air pressure | ||||||
| 1015 HPa | 1015 HPa | 1016 HPa | ||||
| Sunny days | ||||||
| 9 | 7 | 3 | ||||
| Cloudy days | ||||||
| 19 | 17 | 17 | ||||
| Rainy days | ||||||
| 3 | 6 | 11 | ||||
| Snowy days | ||||||
| 0 | 0 | 0 | ||||
September typically has worse weather conditions compared to August. It’s getting colder in September. From +24°C in the day, the average maximum temperature lowers to +21°C. Prepare for more rain. Average rainfall goes from 28 mm to 60 mm. Humidity rises from 71% to 76%. The average wind speed doesn’t change much during September, staying around 1 m/s. The days becoming less sunny, going from 9 sunny days in August to 7 in September.
October brings much the same weather, it remains ok.
Wind
The average wind speed is 2 m/s getting up to 3 m/s which is a light breeze; barely moving the tree leaves.
The average wind speed in Seattle is gradually increasing during September, going from 1 m/s to 1 m/s over the course of the month.
Rain
How was the weather last September in Seattle?
Climate Change over Years
The climate in Seattle in September has not changed much over the last 43 years.
The average temperature was the lowest in 2004 (+19°C) and the highest in 2014 (+26°C). The driest year was 1993 with only 4 mm of rainfall, and the wettest year was 2013 with 186 mm.
FAQ
Is September a good time to visit Seattle?
Can you sunbathe in Seattle in September?
Is Seattle rainy in September?
Is it sunny in Seattle in September?
Other cities in USA
Monthly weather in Seattle
Source of the data
For this page, we’ve looked at the typical weather in Seattle, based on historical hourly weather data from January 1, 1979, to December 31, 2022.
For past dates, we show actual recorded data at the location at that time. Forecasts are based on recorded weather during that day of the year, averaged over the total years for which we have records (unless stated otherwise). The daily temperature is the highest recorded temperature in the shadow during that day.