Climatological Report (Monthly)
Issued by NWS Sterling, VA

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067
CXUS51 KLWX 021840
CLMIAD

CLIMATE REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
134 PM EST TUE JAN 2 2018

...................................

...THE WASHINGTON DULLES DC CLIMATE SUMMARY FOR THE MONTH OF DECEMBER 2017...

CLIMATE NORMAL PERIOD 1981 TO 2010
CLIMATE RECORD PERIOD 1960 TO 2018

WEATHER         OBSERVED          NORMAL  DEPART  LAST YEAR`S
                 VALUE   DATE(S)  VALUE   FROM    VALUE
                                          NORMAL
.............................................................
TEMPERATURE (F)
RECORD
 HIGH              79   12/06/1998
 LOW               -4   12/25/1989
HIGHEST            62   12/23        66      -4
LOWEST              9   12/28        10      -1
AVG. MAXIMUM     44.4              46.0    -1.6     46.9
AVG. MINIMUM     25.6              27.1    -1.5     29.5
MEAN             35.0              36.6    -1.6
DAYS MAX >= 90      0               0.0     0.0
DAYS MAX <= 32      6               2.6     3.4
DAYS MIN <= 32     25              22.6     2.4
DAYS MIN <= 0       0               0.1    -0.1

PRECIPITATION (INCHES)
RECORD
 MAXIMUM         6.74   1969
 MINIMUM         0.32   2007
TOTALS           0.77              2.96   -2.19     2.36
DAILY AVG.       0.02              0.10   -0.08
DAYS >= .01         7               9.9    -2.9
DAYS >= .10         2               6.1    -4.1
DAYS >= .50         0               2.3    -2.3
DAYS >= 1.00        0               0.4    -0.4
GREATEST
 24 HR. TOTAL    0.34   12/23 TO 12/23

SNOWFALL (INCHES)
RECORDS
 TOTAL           24.2   1966
TOTALS            4.6               3.5     1.1
SINCE 7/1         4.6               4.0     0.6
SNOWDEPTH AVG.      0
DAYS >= TRACE       7               1.6     5.4
DAYS >= 1.0         1               1.0     0.0
GREATEST
 SNOW DEPTH         3   12/10
 24 HR TOTAL      4.0

DEGREE_DAYS
HEATING TOTAL     923               882      41      823
 SINCE 7/1       1717              1798     -81     1550
COOLING TOTAL       0                 0       0        0
 SINCE 1/1       1281              1178     103     1559
..............................................................

WIND (MPH)
AVERAGE WIND SPEED              6.6
HIGHEST WIND SPEED/DIRECTION    33/290    DATE  12/25
HIGHEST GUST SPEED/DIRECTION    44/290    DATE  12/25

SKY COVER
POSSIBLE SUNSHINE (PERCENT)   MM
AVERAGE SKY COVER           0.70
NUMBER OF DAYS FAIR            3
NUMBER OF DAYS PC             16
NUMBER OF DAYS CLOUDY         12

AVERAGE RH (PERCENT)     66

WEATHER CONDITIONS. NUMBER OF DAYS WITH
THUNDERSTORM              0     MIXED PRECIP               0
HEAVY RAIN                1     RAIN                       1
LIGHT RAIN                6     FREEZING RAIN              0
LT FREEZING RAIN          0     HAIL                       0
HEAVY SNOW                0     SNOW                       2
LIGHT SNOW                6     SLEET                      0
FOG                      10     FOG W/VIS <= 1/4 MILE      0
HAZE                      2

-  INDICATES NEGATIVE NUMBERS.
R  INDICATES RECORD WAS SET OR TIED.
MM INDICATES DATA IS MISSING.
T  INDICATES TRACE AMOUNT.

&&

...3RD DRIEST DECEMBER ON RECORD AT DULLES...

THE MONTHLY AVERAGE TEMPERATURE WAS 35.0, WHICH IS 1.6 DEGREES BELOW
NORMAL. IT WAS THE COLDEST DECEMBER SINCE 2010, WHEN THE AVERAGE
TEMPERATURE WAS 30.9.

MONTHLY PRECIPITATION WAS 0.77, WHICH IS 2.19 INCHES (74 PERCENT)
BELOW NORMAL. THIS MAKES DECEMBER 2017 THE 3RD DRIEST ON RECORD. IT
WAS THE DRIEST DECEMBER SINCE 1980, WHEN 0.68 INCHES OF
PRECIPITATION FELL.

MONTHLY SNOWFALL WAS 4.6 INCHES, WHICH IS 1.1 INCHES ABOVE NORMAL.
THIS MAKES DECEMBER 2017 THE 18TH SNOWIEST ON RECORD. IT WAS THE
SNOWIEST DECEMBER SINCE 2013, WHEN 4.7 INCHES FELL.

A DAILY RECORD SNOWFALL OF 4.0 INCHES WAS SET ON DECEMBER 9TH. THIS
BROKE THE OLD RECORD OF 2.5 INCHES FROM 2005.

A DAILY RECORD LOW MAXIMUM TEMPERATURE OF 29 DEGREES WAS SET ON
DECEMBER 15TH. THIS BROKE THE OLD RECORD OF 30 FROM 1968.

A DAILY RECORD LOW MAXIMUM TEMPERATURE OF 23 DEGREES WAS SET ON
DECEMBER 28TH. THIS BROKE THE OLD RECORD OF 24 FROM 1993.

TEMPERATURE AND PRECIPITATION RECORDS AT WASHINGTON DULLES
INTERNATIONAL AIRPORT BEGAN IN 1960. SNOWFALL RECORDS BEGAN IN 1962.

ALL CLIMATE DATA ARE CONSIDERED PRELIMINARY UNTIL REVIEWED BY THE
NATIONAL CENTERS FOR ENVIRONMENTAL INFORMATION (NCEI).


$$

RCM



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