558  
CXUS51 KLWX 040008  
CLMIAD  
 
CLIMATE REPORT  
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC  
808 PM EDT FRI MAY 3 2013  
   
...............................  
 
 
...THE WASHINGTON DULLES DC CLIMATE SUMMARY FOR THE MONTH OF APRIL 2013...  
 
CLIMATE NORMAL PERIOD 1981 TO 2010  
CLIMATE RECORD PERIOD 1962 TO 2013  
 
WEATHER OBSERVED NORMAL DEPART LAST YEAR'S  
VALUE DATE(S) VALUE FROM VALUE  
NORMAL    
.........................................................  
 
TEMPERATURE (F)  
RECORD  
HIGH 93 04/06/2010  
04/17/2002  
LOW 17 04/01/1969  
HIGHEST 89 04/10 85 4  
LOWEST 22 04/04 25 -3  
AVG. MAXIMUM 67.7 66.7 1.0 66.5  
AVG. MINIMUM 44.5 42.1 2.4 41.6  
MEAN 56.1 54.4 1.7  
DAYS MAX >= 90 0 0.3 -0.3  
DAYS MAX <= 32 0 0.0 0.0  
DAYS MIN <= 32 3 3.9 -0.9  
DAYS MIN <= 0 0 0.0 0.0  
 
PRECIPITATION (INCHES)  
RECORD  
MAXIMUM 7.35 1973  
MINIMUM 0.33 1985  
TOTALS 2.30 3.47 -1.17 1.82  
DAILY AVG. 0.08 0.12 -0.04  
DAYS >= .01 8 10.7 -2.7  
DAYS >= .10 4 6.8 -2.8  
DAYS >= .50 2 2.0 0.0  
DAYS >= 1.00 1 0.8 0.2  
GREATEST  
24 HR. TOTAL 1.20 04/19  
 
SNOWFALL (INCHES)  
RECORDS  
TOTAL 4.0 1990  
TOTALS 0.0 0.3 -0.3  
SINCE 7/1 12.7 22.0 -9.3  
SNOWDEPTH AVG. 0  
DAYS >= TRACE 0 0.3 -0.3  
DAYS >= 1.0 0 0.1 -0.1  
GREATEST  
SNOW DEPTH 0  
24 HR TOTAL 0.0  
 
DEGREE_DAYS  
HEATING TOTAL 288 335 -47 340  
SINCE 7/1 4414 4572 -158 3729  
COOLING TOTAL 30 17 13 18  
SINCE 1/1 30 20 10 28    
..........................................................  
 
WIND (MPH)  
AVERAGE WIND SPEED 7.7  
HIGHEST WIND SPEED/DIRECTION 31/310 DATE 04/24  
HIGHEST GUST SPEED/DIRECTION 39/310 DATE 04/24  
 
SKY COVER  
POSSIBLE SUNSHINE (PERCENT) MM  
AVERAGE SKY COVER 0.60  
NUMBER OF DAYS FAIR 4  
NUMBER OF DAYS PC 17  
NUMBER OF DAYS CLOUDY 9  
 
AVERAGE RH (PERCENT) 58  
 
WEATHER CONDITIONS. NUMBER OF DAYS WITH  
THUNDERSTORM 1 MIXED PRECIP 0  
HEAVY RAIN 2 RAIN 3  
LIGHT RAIN 10 FREEZING RAIN 0  
LT FREEZING RAIN 0 HAIL 0  
HEAVY SNOW 0 SNOW 0  
LIGHT SNOW 0 SLEET 0  
FOG 9 FOG W/VIS <= 1/4 MILE 2  
HAZE 2  
 
- INDICATES NEGATIVE NUMBERS.  
R INDICATES RECORD WAS SET OR TIED.  
MM INDICATES DATA IS MISSING.  
T INDICATES TRACE AMOUNT.  
 
 
 
AFTER TWO STRAIGHT MONTHS OF BELOW NORMAL TEMPERATURES...THE MONTHLY  
AVERAGE TEMPERATURE FOR APRIL WAS ALMOST TWO DEGREES ABOVE THE  
1981-2010 NORMAL. HOWEVER...THE MONTH ENDED ON A COOL NOTE AS 10 OF  
THE LAST 11 DAYS RECORDED BELOW NORMAL AVERAGE TEMPERATURES.  
 
A WINTER-LIKE COLD PERIOD OCCURRED DURING THE 2ND-4TH. IN  
PARTICULAR...THE LOW TEMPERATURE WAS 24 DEGREES ON THE 3RD AND 22  
DEGREES ON THE 4TH. IT WAS ONLY THE FOURTH OCCURRENCE ON RECORD THAT  
HAD CONSECUTIVE DAYS WITH A LOW TEMPERATURE BELOW 25 DEGREES IN  
APRIL AND THE FIRST IN APRIL SINCE 9-10 APRIL 1977.  
 
THE LOW TEMPERATURE OF 22 DEGREES ON THE 4TH TIED THE DAILY RECORD  
LOW FOR DULLES THAT WAS PREVIOUSLY SET IN 1965. IT WAS THE LOWEST  
TEMPERATURE DURING APRIL SINCE 7 APRIL 2002 WHEN IT WAS ALSO 22  
DEGREES.  
 
A SUMMER-LIKE PERIOD FROM THE 8TH-11TH FEATURED FOUR STRAIGHT DAYS  
OF AT LEAST 80 DEGREES. 2013 WAS ONLY THE SECOND YEAR ON RECORD THAT  
RECORDED FOUR CONSECUTIVE 80-DEGREE DAYS THROUGH THE FIRST HALF OF  
APRIL /THE OTHER WAS 5-8 APRIL 2010/.  
 
THE HIGH TEMPERATURE OF 89 DEGREES ON THE 10TH SET A DAILY RECORD  
HIGH FOR DULLES. IT BROKE THE OLD RECORD OF 78 SET IN 1922.  
 
RAINFALL FOR THE MONTH WAS BELOW NORMAL. HALF OF THE MONTHLY  
PRECIPITATION FELL ON THE 19TH.  
 
 
JRK/SMZ  
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