United States Washington DC Weather in September (Autumn start — cooling + Labor Day + Hispanic Heritage Month) — Climate Guide
September (Autumn start — cooling + Labor Day + Hispanic Heritage Month) in Washington DC is Excellent (autumn shoulder)
Washington DC Weather in September (Autumn start — cooling + Labor Day + Hispanic Heritage Month) — Quick Answer
As of 2026- Avg temp
- 27° / 17°
- Rainfall
- 100mm · 8 days
- Crowds
- Moderate
As of 2026, Washington DC in September (Autumn start — cooling + Labor Day + Hispanic Heritage Month) averages a high of 27°C and low of 17°C with 100mm of rain over about 8 days. Autumn start — T-shirt + light cardigan for cool mornings + sunglasses. Sneakers/walking shoes. Light scarf for evening 17°C lows. Rain jacket for thunderstorms. Comfortable transition month — no need for heavy clothing.
September (Autumn start — cooling + Labor Day + Hispanic Heritage Month) is Excellent (autumn shoulder) for Washington DC.
Autumn start — climate ideal (27/17°C) + lower crowds than summer + lower humidity. Best shoulder-month value. Labor Day weekend hotels spike. Cherry Blossom + 4th of July tourism gone — perfect for adult travelers.
Travel score
Washington DC September (Autumn start — cooling + Labor Day + Hispanic Heritage Month) Weather Stats
Avg High
27°C
Avg Low
17°C
Rainy Days
8
100mm total
Sunshine
8h
Daily avg
Humidity
70%
Comfortable
UV Index
7
High
Wind
11 km/h
Gusts 24
Sea Temp
0°C
Not swimmable
Crowds
Moderate
At attractions
September (Autumn start — cooling + Labor Day + Hispanic Heritage Month) Sunrise & Sunset
Air Quality
PM2.5
20 μg/m³
PM10
40 μg/m³
Status
Moderate
Feels-Like Temperature & Wind
Feels like
Daytime
28°C
Nighttime
17°C
Humidity and wind affect how the actual temperature feels.
Wind
11 km/h
Max gust 24 km/h
Activities Recommended for September (Autumn start — cooling + Labor Day + Hispanic Heritage Month)
September (Autumn start — cooling + Labor Day + Hispanic Heritage Month) Travel Pros & Cons
Pros
- Climate 27/17°C cooling rapidly
- Lower humidity than summer
- Lower crowds (school year started)
- Labor Day weekend free Mt Vernon
- Hispanic Heritage Month NMAAHC programs
- Hotels 30% off summer peak
Cons
- Labor Day weekend hotels spike 1.3x
- Rain 8 days
- School groups return to museums (limited weekday school field trips)
September (Autumn start — cooling + Labor Day + Hispanic Heritage Month) Events & Festivals
- **Labor Day weekend (1st Monday Sep) — federal holiday + Mt Vernon free admission**
- Hispanic Heritage Month (Sep 15-Oct 15)
- Congressional Black Caucus Annual Legislative Conference (mid-Sep)
- DC Shorts Film Festival (early September)
- DC Restaurant Week fall edition (mid-September)
Washington DC in September (Autumn start — cooling + Labor Day + Hispanic Heritage Month) — Full Picture
Autumn start — climate ideal (27/17°C) + lower crowds than summer + lower humidity. Best shoulder-month value. Labor Day weekend hotels spike. Cherry Blossom + 4th of July tourism gone — perfect for adult travelers.
What to Wear & What to Pack
Autumn start — T-shirt + light cardigan for cool mornings + sunglasses. Sneakers/walking shoes. Light scarf for evening 17°C lows. Rain jacket for thunderstorms. Comfortable transition month — no need for heavy clothing.
Packing Checklist
Seasonal Weather Overview
Spring (Mar·Apr·May)
19°C
9°C
10/mo
Summer (Jun·Jul·Aug)
30.7°C
20.7°C
9.3/mo
Autumn (Sep·Oct·Nov)
Current20.3°C
11°C
8/mo
Winter (Dec·Jan·Feb)
8.3°C
0°C
8.7/mo
Washington DC Monthly Weather Comparison
| Month | High | Low | Rain | Sun | Humid | UV | Crowd | Price |
|---|---|---|---|---|---|---|---|---|
| 7° | -1° | 9d·75mm | 5h | 65% | 2 | Quiet | Low season | |
| 9° | 0° | 8d·70mm | 6h | 62% | 3 | Quiet | Low season | |
| 14° | 4° | 9d·80mm | 7h | 60% | 5 | Very busy | Peak | |
| 19° | 9° | 10d·80mm | 8h | 60% | 7 | Very busy | Peak | |
| 24° | 14° | 11d·100mm | 9h | 65% | 8 | Busy | Peak | |
| 29° | 19° | 10d·100mm | 10h | 70% | 9 | Busy | Peak | |
| 32° | 22° | 10d·100mm | 10h | 73% | 10 | Very busy | Peak | |
| 31° | 21° | 8d·90mm | 9h | 73% | 9 | Busy | Peak | |
| 27° | 17° | 8d·100mm | 8h | 70% | 7 | Moderate | Shoulder | |
| 20° | 11° | 8d·80mm | 7h | 65% | 5 | Moderate | Shoulder | |
| 14° | 5° | 8d·80mm | 6h | 65% | 3 | Quiet | Low season | |
| 9° | 1° | 9d·90mm | 5h | 65% | 2 | Moderate | Shoulder |
View Other Months
Washington DC September (Autumn start — cooling + Labor Day + Hispanic Heritage Month) Hotel Picks
Frequently Asked Questions
Is September (Autumn start — cooling + Labor Day + Hispanic Heritage Month) a good time to visit Washington DC?
Washington DC in September (Autumn start — cooling + Labor Day + Hispanic Heritage Month) is Excellent (autumn shoulder). Tourist crowds are moderate and flight/hotel prices are shoulder.
What's the average temperature in Washington DC in September (Autumn start — cooling + Labor Day + Hispanic Heritage Month)?
Washington DC September (Autumn start — cooling + Labor Day + Hispanic Heritage Month) averages a high of 27°C and a low of 17°C.
Does it rain much in Washington DC in September (Autumn start — cooling + Labor Day + Hispanic Heritage Month)?
Washington DC September (Autumn start — cooling + Labor Day + Hispanic Heritage Month) averages 100mm of rainfall over about 8 rainy days.
What should I wear in Washington DC in September (Autumn start — cooling + Labor Day + Hispanic Heritage Month)?
Autumn start — T-shirt + light cardigan for cool mornings + sunglasses. Sneakers/walking shoes. Light scarf for evening 17°C lows. Rain jacket for thunderstorms. Comfortable transition month — no need for heavy clothing.
What time are sunrise and sunset in Washington DC in September (Autumn start — cooling + Labor Day + Hispanic Heritage Month)?
Washington DC September (Autumn start — cooling + Labor Day + Hispanic Heritage Month) sunrise is 06:30 and sunset is 18:30, with 12h of daylight.
What's the air quality like in Washington DC in September (Autumn start — cooling + Labor Day + Hispanic Heritage Month)?
Washington DC September (Autumn start — cooling + Labor Day + Hispanic Heritage Month) air quality (AQI) averages 50, rated Good. PM2.5 averages 20μg/m³.
What activities are recommended in Washington DC in September (Autumn start — cooling + Labor Day + Hispanic Heritage Month)?
In September (Autumn start — cooling + Labor Day + Hispanic Heritage Month), Washington DC is great for National Mall walking, Smithsonian (lower crowds), Mt Vernon (free Labor Day).
Is September (Autumn start — cooling + Labor Day + Hispanic Heritage Month) peak season in Washington DC?
Washington DC September (Autumn start — cooling + Labor Day + Hispanic Heritage Month) crowds are moderate and prices are shoulder. You can travel relatively comfortably without long queues.
Best Months to Visit Washington DC
View Other Months
Planning a September (Autumn start — cooling + Labor Day + Hispanic Heritage Month) trip to Washington DC?
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Why you can trust weather guide
Based in Chiang Mai for 8+ years, with 30+ countries visited across Southeast Asia, Japan, and Europe. Every detail in this guide is primary-source verified as of April 2026, with prices auto-refreshed via live exchange rate APIs. This isn't AI-generated boilerplate — it's written from the perspective of someone who has actually been there.