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Weather in Washington DC in September

Updated: July 26, 2023

This post takes a look at the September weather in Washington, D.C, with tips on what you should wear as well as ideas for things to do.


During early September you can expect to encounter daytime high temperature mainly in the mid-80s F (about 29 C) while early in the morning the temperatures will most likely to be in the mid to upper 60s F (about 19 C).

DC September Temperatures

On average, about 2 or 3 days during this month will see temperatures reaching or exceeding 90 F (about 32 C) but this is much better than the month of August when 8-9 days typically reach 90 F or higher.

DC is a humid mid-Atlantic area which means it often feels hotter than the temperature actually reads. The best way to combat this is to make sure you have water with you.

Late September Temperatures DC

Towards the end of this month, daytime highs fall to the mid-70s F (about 24 C) and morning lows temperatures average in the mid to upper 50s F (about 14 C).


Clear or mostly sunny skies occur about 60% of the time during September while cloudy skies prevail on about 1 out of 4 days.

How Much Sun in DC in September

Some rainfall occurs on about 8 days during this month; however, heavy rains of 0.5 inches (12.7 mm) or more occur on only 2 or 3 days.

The majority of DC rain comes in waves, meaning that it's more likely to have a storm appear with heavy rain for thirty minutes than a full day of rain.


Be sure to read out post on What to Wear and Pack in DC for advice all year round on DC weather and how to prepare for it.

September begins the nicer weather for DC where the humidity calms down and the temperatures drop to something a bit more comfortable.

Always bring a couple of comfortable walking shoes and an umbrella for those sneaky showers.

If you plan on spending the day taking our afternoon tours like Arlington National Cemetery or National Mall, we recommend some sunscreen as well.

What to Wear in September in Washington DC


You won’t need a jacket or long-sleeved shirts for most days, but if you're coming later in the month or plan to stay out in the evenings, a light jacket and layers are recommended.

Often, international guests are unprepared for how DC buildings can be so cold. Americans love air conditioning.

So, that light, long-sleeved shirt could come in handy during the day.


Below are 10 top things to do in DC in September.

Be sure to read our full post on what to do in DC in September which includes free things to do, night and family-friendly activities and attractions.

We also recommend reading our definitive post on the best things to do in DC any time of year.

And if you are planning on visiting many of DC’s top attractions, then you should consider a tourist attraction discount pass as you could save up to 50% of retail ticket prices to tours, attractions, and restaurants.

Be sure to check out all the top things to do in September in our main post.

Seasonal Outlook

July to September 2022 Washington, DC

There is an 85% chance for normal to above normal temperatures and a 77% chance for normal to above normal rainfall

About The Author

Fred Pickhardt

Fred is a marine meteorologist and sailed briefly with American Export Lines in the Far East trade. He has extensive experience in weather analysis, weather forecasting, and forensic weather event reconstructions. Fred founded Ocean Weather Services and currently provides forensic marine weather reports to the maritime industry.
Updated: July 26th, 2023
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