Washington Weather in September
During September, Washington experiences high daytime temperatures of 27°C (81°F) and cooler nights around 17°C (63°F). Expect quite a bit of rainfall. Around 94 mm (3.7 in) is typical.
Rainfall in Washington in September
Climate statistics over the past 30 years suggest around 9 days of rain, with 94 mm (3.7 in) average for the month. The rain this month tends to fall in heavier spells rather than light drizzle. When it rains, showers can be significant.
Temperature in Washington in September
September is a perfect month in Washington, with 27°C (81°F) during the day and 17°C (63°F) at night. Overall, the month follows a fairly predictable daily temperature pattern. Nights cool down to 17°C (63°F), so a light jacket or extra layer is useful once the sun goes down. On the plus side, the cooler nights make for comfortable sleeping conditions.
Sunshine in Washington in September
The city usually sees around 225 hours of sunlight, indicating many sunny days — a great month for sightseeing.
Wind Speed in Washington in September
Wind speeds average 4 m/s (8 knots) during September. At this speed, expect moderate winds that can raise dust and move small branches. Since this is an average, some days have gentle light winds while others experience stronger breezes that are quite noticeable.So this is a great month to visit if you prefer dry days with pleasant temperatures.
Check the conditions for any month of the year.
For a detailed overview over the year and the best time to visit the United States of America, check out our Washington's climate page.
Washington Temperature in September
Min Temperature
17°C (63°F)
Max Temperature
27°C (81°F)
Chance of Rain
30%
Precipitation
94 mm (3.7 in)
Rainy days
9 days
Humidity
68% *
Windspeed
4 m/s (8 knots) *
Sunshine
225 hours *
Percentage Sunshine
60% *
Daily Historical Temperatures
50-year average (1976-2025)
Based on our historical records, temperatures in Washington typically drop from around 29°C (84°F) at the start of September to approximately 24°C (75°F) by the end. Nights are pleasant, with lows typically ranging from 14°C (57°F) to 20°C (68°F).
Average temperatures in September
Daily Historical Precipitation
50-year average (1976-2025)
Average daily rainfall for each day of the month based on long-term records.
Average precipitation in September
Historical weather for Washington in September
Browse day-by-day weather records for Washington spanning 51 years. Select any month and year to see actual temperatures, rainfall, and conditions recorded on each day.
Washington historical weather extremes in September
According to our 49 years of weather records for Washington, the following extremes were recorded between 1976 and 2025.
- The warmest day in September was on September 2, 1980, with a maximum of 38°C (100°F).
- The lowest overnight temperature recorded in September was 6°C (43°F) (September 22, 1997).
Best Places in the United States of America in September
Find out more about the weather in the United States of America and which places have the best travel conditions in this month. See all of the United States of America in September →
perfect weather
pleasant
tolerable
unpleasant
poor
What to Wear in Washington in September
Warm temperatures in September make for comfortable sightseeing weather. Pack breathable fabrics like cotton shirts, knee-length shorts or skirts, and comfortable walking shoes. A thin long sleeve for indoor spaces is handy. Prepare for significant rainfall with proper waterproof clothing and shoes. You'll definitely want to pack sunglasses and sunscreen. There will be plenty of bright sunshine this month.What To Do in Washington in September
We rated the following activities from 1 (least suitable) to 10 (best) to do.
Check the conditions for any month of the year.
For a detailed overview over the year and the best time to visit the United States of America, check out our Washington's climate page.
Temperature Rainfall Sunshine Humidity Wind Speed
See the full Washington climate overview or explore weather in the United States of America.
