Contents
- Weather in September
- Frequently asked questions
- Average temperature in September
- Average pressure in September
- Average wind speed in September
- Average humidity in September
- Average rainfall in September
- Average rainfall days in September
- Average snowfall in September
- Average snowfall days in September
- Average daylight in September
- Average sunshine in September
- Average sunshine days in September
- Average UV index in September
- Average cloud cover in September
- Average visibility in September
Weather in September
Temperature
September's onset in Washington corresponds with a subtle shift in the average high-temperature, slightly moving from 85.8°F (29.9°C) in August to a still moderately hot 78.4°F (25.8°C). Nighttime temperature in Washington experiences an average drop to a comfortable 61.9°F (16.6°C) in September.Humidity
In Washington, the average relative humidity in September is 74%.Rainfall
In Washington, in September, during 12.5 rainfall days, 1.85" (47mm) of precipitation is typically accumulated. In Washington, District of Columbia, during the entire year, the rain falls for 149.1 days and collects up to 26.14" (664mm) of precipitation.Snowfall
In Washington, snow does not fall in April through November.Daylight
In Washington, the average length of the day in September is 12h and 26min.On the first day of September in Washington, sunrise is at 6:37 am and sunset at 7:38 pm. On the last day of the month, sunrise is at 7:03 am and sunset at 6:51 pm EDT.
Sunshine
The average sunshine in September is 9h.UV index
In September, the average daily maximum UV index in Washington, District of Columbia, is 5. A UV Index value of 3 to 5 symbolizes a medium vulnerability from exposure to the Sun's UV radiation for ordinary individuals.Note: A maximum high UV index of 5 in September translates into the following recommendations:
Heed the precautions - Protecting the skin and eyes from damage is compulsory. Avoiding the Sun's peak radiation during midday hours is essential for health and safety. A hat with a broad brim is indispensable, filtering out up to half of UV rays.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the usual temperature for Washington in September?
What is the average humidity in September in Washington?
How many days does it rain in September in Washington?
When it does not snow in Washington?
What is the average length of the day in September in Washington?
What time are sunrise and sunset in September in Washington?
How long on average sun shines in September in Washington?
How high is the UV index in September in Washington?
Average temperature in September
Washington, DC
- Average high temperature in September: 78.4°F
The warmest month (with the highest average high temperature) is July (88°F).
The month with the lowest average high temperature is January (40.6°F).
- Average low temperature in September: 61.9°F
The month with the highest average low temperature is July (69.1°F).
The coldest month (with the lowest average low temperature) is January (27.5°F).
Average pressure in September
Washington, DC
- Average pressure in September: 30.05"Hg
The month with the highest atmospheric pressure is November (30.14"Hg).
The month with the lowest atmospheric pressure is June (29.95"Hg).
Average wind speed in September
Washington, DC
- Average wind speed in September: 5.7mph
The windiest month (with the highest average wind speed) is March (7.9mph).
The calmest month (with the lowest average wind speed) is August (5mph).
Average humidity in September
Washington, DC
- Average humidity in September: 74%
The month with the highest relative humidity is May (76%).
The months with the lowest relative humidity are April and July (71%).
Average rainfall in September
Washington, DC
- Average rainfall in September: 1.85"
The wettest month (with the highest rainfall) is August (3.46").
The driest month (with the least rainfall) is January (1.57").
Average rainfall days in September
Washington, DC
- Average rainfall days in September: 12.5 days
The month with the highest number of rainy days is July (16.4 days).
The month with the least rainy days is November (8.1 days).
Average snowfall in September
Washington, DC
- Average snowfall in September: 0"
The month with the highest snowfall is January (2.17").
The months with the least snowfall are April, May, June, July, August, September, October and November (0").
Average snowfall days in September
Washington, DC
- Average snowfall days in September: 0 days
The months with the highest number of snowfall days are January and February (3.8 days).
The months with the least snowfall days are April, May, June, July, August, September and October (0 days).
Average daylight in September /
Average sunshine in September
Washington, DC
- Average daylight in September: 12h and 2min
The month with the longest days is June (Average daylight: 14h and 54min).
The month with the shortest days is December (Average daylight: 9h and 30min).
- Average sunshine in September: 9h and 0min
The month with the most sunshine is July (Average sunshine: 10h and 42min).
The months with the least sunshine are January, February and December (Average sunshine: 5h and 6min).
Average sunshine days in September
Washington, DC
- Average sunshine days in September: 15.7 days
The month with the most sunshine days is November (20 days).
The month with the least sunshine days is May (12.8 days).
Average UV index in September
Washington, DC
- Average UV index in September: 5
The month with the highest UV index is June (UV index 7).
The months with the lowest UV index are January and December (UV index 2).
Average cloud cover in September
Washington, DC
- Average cloud cover in September: 36
The month with the most cloud cover is March (Cloud cover 46).
The month with the least cloud cover is July (Cloud cover 30).
Average visibility in September
Washington, DC
- Average visibility in September: 6mi
The months with the highest visibility are January, February, March, April, June, July, August, September, October, November and December (6mi).
The month with the lowest visibility is May (5mi).
Washington, District of Columbia, USA
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