National Harbor Weather in September

September in National Harbor averages 27°C (81°F) during the day and 17°C (63°F) at night. Quite a bit of rainfall is typical this month, with around 101 mm (4 in) on average. An umbrella is a good idea.

Rainfall in National Harbor in September

The climate data from previous years indicates about 9 days of rain, averaging 101 mm (4 in) for the month. Rainfall intensity is on the higher side this month. Expect more substantial showers rather than light, passing rain.

Temperature in National Harbor in September

In September, expect high temperatures in National Harbor, with highs of 27°C (81°F) and lows of 17°C (63°F) at night. This kind of day-to-night contrast is typical for this time of year. 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 National Harbor in September

Expect a lot of sunshine this month, with about 225 hours of sun. These sunny conditions add to the overall experience.

Wind Speed in National Harbor 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.

If you prefer dry days with pleasant temperatures, April typically offers the best circumstances. If you're seeking pleasant, dry and sunny weather somewhere else in the world, our weather planner can help you explore other options.

Select a Month

Check the conditions for any month of the year.

• January
• February
• March
• April

• May
• June
• July
• August

• September
• October
• November
• December

For a detailed overview over the year and the best time to visit the United States of America, check out our National Harbor's climate page.

National Harbor Temperature in September

Min Temperature 17°C (63°F)  

Max Temperature 27°C (81°F)  

Chance of Rain 29%  

Precipitation 101 mm (4 in)  

Rainy days 9 days  

Humidity 68% *  

Windspeed 4 m/s (8 knots) *  

Sunshine 225 hours *  

Percentage Sunshine 60% *  

* Data from: Washington DC, the United States of America (7 KM, 4 Miles).

What to Wear in National Harbor 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 National Harbor in September

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

Swimming

9/10

Cycling

7/10

Walking

7/10

Camping

6/10

Outdoor sports

7/10

Select a Month

Check the conditions for any month of the year.

• January
• February
• March
• April

• May
• June
• July
• August

• September
• October
• November
• December

For a detailed overview over the year and the best time to visit the United States of America, check out our National Harbor's climate page.

More climate data for National Harbor

Temperature Rainfall Sunshine Humidity Wind Speed

See the full National Harbor climate overview or explore weather in the United States of America.