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United States of America

DULLES, VIRGINIA


Home > North America > United States > Virginia
Elevation: 88 meters     Latitude: 38 57N     Longitude: 077 27W

WEATHER
 
CURRENT CONDITIONS

Sunrise/Set
06:26 am
07:51 pm

Local Time
2:05 pm EDT
19 April, 2024
 
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MONTHLY - ALL WEATHER AVERAGES   [ Show Summary ]
[ °F ]   °C
TEMPERATURE 
Average Temperature
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
C12.90.72.36.812.417.322.424.824.119.913.382.6

Average High Temperature
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
C19.15.8813.119.323.928.831.130.326.320.114.27.8

Average Low Temperature
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
C6.8-4.5-3.30.55.610.716.118.617.913.56.61.8-2.7

Highest Recorded Temperature
Years on Record: 50  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
C40.623.926.131.733.936.138.940.64037.234.428.926.1

Lowest Recorded Temperature
Years on Record: 50  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
C-27.8-27.8-25.6-18.3-8.3-2.22.253.3-1.1-9.4-12.8-20

Average Heat Index Temperature
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
C13.10.72.36.812.617.622.725.324.219.913.37.82.7

Average Wind Chill Temperature
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
C11.8-2.3-0.44.711.817.422.324.723.719.712.86.50.2

Average Number of Days Above 100F/38C
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Days0.4------------------0.20.1------------

Average Number of Days Above 90F/32C
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Days30.3---------0.31.15.611.68.92.70.1------

Average Number of Days Above 80F/26C
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Days109.6------0.83.810.122.327.927.114.13.10.3---

Average Number of Days Above 70F/21C
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Days171.30.30.53.71121.628.630.930.826.513.33.40.6

Average Number of Days Above 60F/15C
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Days229.72.63.210.721.329.530313129.825.312.23

Average Number of Days Above 50F/10C
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Days280.37.39.419.627.930.93031313030.622.510.1

Average Number of Days Above 40F/4C
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Days330.617.419.928.4303130313130312921.9

Average Number of Days Below 70F/21C
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Days349.13128313030.927.523.825.929.1313031

Average Number of Days Below 60F/15C
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Days27930.92830.929.425.912.24.87.219.329.429.931

Average Number of Days Below 50F/10C
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Days217.230.727.829.62413.62.30.40.77.222.827.630.5

Average Number of Days Below 40F/4C
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Days157.429.326.124.212.53.20.1------1.111.721.228.1

Average Number of Days Below 32F/0C
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Days102.524.321.115.23.90.2------------2.912.422.6

Average Number of Days Below 20F/-6C
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Days27.310.86.72.3---------------------16.5

Average Number of Days Below 10F/-12C
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Days5.12.810.2------------------------1.1

Average Number of Days Below 0F/-17C
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Days0.90.60.1---------------------------0.1



PRECIPITATION 
Average Precipitation
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
mm1054.168.668.686.488.9116.8101.69488.999.183.886.476.2

Average Number of Days With Precipitation
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Days118.79.9910.510.712.210.910.89.48.77.69.19.9

Avg. No. of Days w/Precip. Above 0.1in/2.5mm
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Days73.45.75.46.86.87.56.66.55.65.85.15.56.1

Avg. No. of Days w/Precip. Above 0.5in/13mm
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Days27.51.81.72.123.22.62.42.12.62.32.42.3

Avg. No. of Days w/Rain Above 1in/25mm
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Days10.10.50.70.90.811111.10.80.90.4

Average Precipitable Water
Years on Record: 20  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
cm.2.11.111.31.62.33.23.63.52.81.91.51.2



PRECIPITATION - RAIN 
Average Number of Rainy Days
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Days11710910101210111098910

Average Number of Days With Thunderstorms
Years on Record: 33  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Days28------124665211---

Most Rain Reported in a Month
Years on Record: 33  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
mm1400160140190180260210180270280230190170

Least Recorded Rainfall
Years on Record: 33  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
mm73010---20---2010202010------10



PRECIPITATION - SNOW 
Average Snowfall
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
cm55.918.519.37.10.8------------------1.38.9

Average Number of Days With Snow
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Days9.83.52.61.50.3------------------0.31.6

Avg. No. of Days w/Snow Above 1in/2.5cm
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Days5.61.91.60.90.1------------------0.11

Avg. No. of Days w/Snow Above 3in/7.5cm
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Days2.610.90.3---------------------0.10.3

Avg. No. of Days w/Snow Above 5in/12.7cm
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Days0.80.20.30.1------------------------0.2

Avg. No. of Days w/Snowfall Above 10in/25cm
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Days0.30.10.1---------------------------0.1

Avg. # of Days w/Snow Depth Above 1in/2.5cm
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Days15.75.55.51.60.1------------------0.22.8

Avg. # of Days w/Snow Depth Above 3in/7.5cm
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Days8.52.93.10.6---------------------0.11.8

Avg. # of Days w/Snow Depth Above 5in/12.7cm
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Days4.21.61.70.3------------------------0.6

Avg. # of Days w/Snow Depth Above 10in/25cm
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Days1.60.60.80.1------------------------0.1



HUMIDITY 
Average Relative Humidity
Years on Record: 20  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
%67.563.761.161.36268.971.871.171.772.772.16866.2

Average Morning Relative Humidity
Years on Record: 33  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
%82777778778284868989888278

Average Evening Relative Humidity
Years on Record: 33  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
%53575249465354545555525457

Average Dew Point
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
C6.6-5.4-4.3-0.94.61116.418.517.814.27.71.8-3.1



DEGREE DAYS 
Heating Degree Days
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Days471798680664733513015---256298560882

Cooling Degree Days
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Days1178------31772237363324141192---

Growing Degree Days
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Days378099531814106728287875362186414



BAROMETER 
Average Sea Level Pressure
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
mbar1017.61019.51018.91017.41015.51015.61015.21015.71016.91018.21019.31019.71020



SKY CONDITIONS 
Average Length of Day
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Hours12.710.311.212.413.714.815.415.114.112.811.610.510

Average Number of Days With Fog
Years on Record: 33  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Days170131012101416192018141212

Average Number of Clear Days
Years on Record: 31  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Days917877768891177

Average Number of Cloudy Days
Years on Record: 31  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Days168171416141412121212121517

Average Number of Partly Cloudy Days
Years on Record: 31  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Days1067689101211119887

Average Percent Chance - Clear Skies
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
%18.518.818.820.518.916.113.713.115.521.425.12118.6

Average Percent Chance - Scattered Clouds
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
%10.58.28.68.2910.513.71514.511.39.68.98.4

Average Percent Chance - Few Clouds
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
%14.112.412.712.612.514.315.816.716.315.214.813.212.3

Average Percent Chance - Broken Clouds
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
%20.317.116.716.819.120.92627.424.620.118.418.817.7

Average Percent Chance - Overcast Skies
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
%36.643.643.141.940.538.330.827.928.931.932.138.143

Average Total Sky Cover
Years on Record: 20  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
%5963.161.461.660.859.85958.15654.85160.362

Average Opaque Sky Cover
Years on Record: 20  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
%53.158.155.756.754.353.251.752.949.649.645.354.356.7



WIND 
Average Wind Speed
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
km/h11.312.612.913.81311.310.19.599.710.111.311.7

Highest Reported Hourly Wind Speed
Years on Record: 49  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
km/h9562.87470.87464.49577.269.259.562.869.266

Average Percent Chance - Calm Winds
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
%12.810.810.48.69.911.313.214.615.414.915.914.913.6

Average Primary Wind Direction
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
°306360360358327.1287.1278274.3233.6209.4271.8355.9360

Average Secondary Wind Direction
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
°212.7183.6140.1110.3215.1261.6280.1268.9215.6249.1233.5206.4184.4

Average Wind Vector Direction
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
°275.6301.4303.8305.6291.5249.4236.8240.4247.7259286.1290.2296.7



SOLAR RADIATION 
Average Daily Solar Radiation - Global
Years on Record: 22  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Mj/m213.97.19.913.416.819.220.320.117.915.312.186.2

Average Daily Solar Radiation - Diffuse
Years on Record: 22  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Mj/m25.8345.57.28.38.98.67.65.94.33.22.7

Average Daily Solar Radiation - Reflected
Years on Record: 22  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Mj/m215.311.213.415.61717.617.817.917.31716.312.310.3

Average Daily Solar Radiation - Direct
Years on Record: 22  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Mj/m21511.313.414.715.816.917.417.616.416.616.612.610.4

Maximum Daily Solar Radiation - Global
Years on Record: 22  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Mj/m213.97.19.913.416.819.220.320.117.915.312.186.2

Maximum Daily Solar Radiation - Diffuse
Years on Record: 22  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Mj/m25.934.15.77.48.69.18.87.86.34.63.32.7

Maximum Daily Solar Radiation - Reflected
Years on Record: 22  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Mj/m218.113.416.718.919.420.720.719.519.319.920.615.612.3

Maximum Daily Solar Radiation - Direct
Years on Record: 22  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Mj/m219.61418.519.82023.123.620.82021.523.117.413

Minimum Daily Solar Radiation - Global
Years on Record: 22  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Mj/m211.467.910.814.512.717.117.915.813.19.85.94.8

Minimum Daily Solar Radiation - Diffuse
Years on Record: 22  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Mj/m25.42.83.65.16.87.78.38.37.35.43.52.82.6

Minimum Daily Solar Radiation - Reflected
Years on Record: 22  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Mj/m212.199.912.114.511.715.116.115.314.112.38.17.2

Minimum Daily Solar Radiation - Direct
Years on Record: 22  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC  
Mj/m210.18.38.69.711.87.212.113.912.912.210.876.4




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