Weather in Washington in September 2025
Average weather
Average temperature in Washington in September
Going from a maximum of +97°F during the day to a minimum of +54°F during the night, the temperature in September averages around +81°F.
The average maximum temperature goes down 12% by the end of the month, compared with the beginning of the month, from +81°F to +75°F.
Is Washington warm or cold in September?
Washington is typically warm in September.
Maximum temperatures go down compared to the previous month from +86°F to +79°F. The minimum temperature also goes down from +70°F to +63°F.
It’s generally warm, but pack a long-sleeve shirt for evenings.
Take a look at how September is compared to other months in Washington:
Climate in Washington in September
| August | September | October | ||||
|---|---|---|---|---|---|---|
| Avg. temperature | ||||||
| +86°F | +79°F | +68°F | ||||
| Min. temperature | ||||||
| +48°F | +43°F | +30°F | ||||
| Max. temperature | ||||||
| +102°F | +99°F | +95°F | ||||
| Rainfall | ||||||
| 112 mm | 117 mm | 96 mm | ||||
| Wind | ||||||
| 2 m/s | 2 m/s | 3 m/s | ||||
| Humidity | ||||||
| 68% | 70% | 70% | ||||
| Air pressure | ||||||
| 1015 HPa | 1017 HPa | 1018 HPa | ||||
| Sunny days | ||||||
| 3 | 5 | 7 | ||||
| Cloudy days | ||||||
| 11 | 11 | 12 | ||||
| Rainy days | ||||||
| 13 | 12 | 11 | ||||
| Snowy days | ||||||
| 0 | 0 | 0 | ||||
September weather is still as good as in August. It’s getting colder in September. From +86°F in the day, the average maximum temperature lowers to +79°F. Prepare for more rain. Average rainfall goes from 112 mm to 117 mm. Humidity rises from 68% to 70%. The average wind speed doesn’t change much during September, staying around 2 m/s. The good news is there are likely to be more sunny days in September, from 3 to 5.
October brings much the same weather, it remains good.
Wind
The average wind speed is 3 m/s getting up to 6 m/s which is a medium breeze. You can feel it, especially getting out of the water.
The average wind speed in Washington is gradually increasing during September, going from 2 m/s to 3 m/s over the course of the month.
Rain
How was the weather last September in Washington?
Climate Change Over the Years
The climate in Washington in September has not changed that much over the last 43 years.
The average temperature was the lowest in 1996 (+64°F) and the highest in 2023 (+70°F). The driest year was 2007 with only 654 mm of rainfall, and the wettest year was 2022 with 1801 mm.
FAQ
Is September a good time to visit Washington?
Can you sunbathe in Washington in September?
Is Washington rainy in September?
Is it sunny in Washington in September?
Other cities in USA
Monthly weather in Washington
Source of the data
For this page, we’ve looked at the typical weather in Washington, based on historical hourly weather data from January 1, 1979, to December 31, 2023.
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.