Climatological Report (Monthly)
Issued by NWS Sterling, VA

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CXUS51 KLWX 012130
CLMIAD

CLIMATE REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
530 PM EDT SUN OCT 1 2017

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

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

CLIMATE NORMAL PERIOD 1981 TO 2010
CLIMATE RECORD PERIOD 1960 TO 2017

WEATHER         OBSERVED          NORMAL  DEPART  LAST YEAR`S
                 VALUE   DATE(S)  VALUE   FROM    VALUE
                                          NORMAL
.............................................................
TEMPERATURE (F)
RECORD
 HIGH              99   09/11/1983
                        09/10/1983
                        09/02/1980
 LOW               30   09/24/1974
HIGHEST            89   09/27        91      -2
                        09/25
                        09/24
LOWEST             47   09/10        39       8
AVG. MAXIMUM     78.8              79.4    -0.6       MM
AVG. MINIMUM     58.2              56.3     1.9       MM
MEAN             68.5              67.9     0.6
DAYS MAX >= 90      0               2.7    -2.7
DAYS MAX <= 32      0               0.0     0.0
DAYS MIN <= 32      0               0.0     0.0
DAYS MIN <= 0       0               0.0     0.0

PRECIPITATION (INCHES)
RECORD
 MAXIMUM        11.26   1975
 MINIMUM         0.15   2005
TOTALS           1.75              3.92   -2.17       MM
DAILY AVG.       0.06              0.13   -0.07
DAYS >= .01         5               8.7    -3.7
DAYS >= .10         3               5.8    -2.8
DAYS >= .50         2               2.6    -0.6
DAYS >= 1.00        0               1.1    -1.1
GREATEST
 24 HR. TOTAL    0.66   09/02 TO 09/02

DEGREE_DAYS
HEATING TOTAL      40                56     -16       MM
 SINCE 7/1         41                58     -17       MM
COOLING TOTAL     155               141      14       MM
 SINCE 1/1       1216              1157      59       MM
..............................................................

WIND (MPH)
AVERAGE WIND SPEED              5.7
HIGHEST WIND SPEED/DIRECTION    24/330    DATE  09/30
HIGHEST GUST SPEED/DIRECTION    31/320    DATE  09/30

SKY COVER
POSSIBLE SUNSHINE (PERCENT)   MM
AVERAGE SKY COVER           0.50
NUMBER OF DAYS FAIR            8
NUMBER OF DAYS PC             18
NUMBER OF DAYS CLOUDY          4

AVERAGE RH (PERCENT)     75

WEATHER CONDITIONS. NUMBER OF DAYS WITH
THUNDERSTORM              1     MIXED PRECIP               0
HEAVY RAIN                3     RAIN                       3
LIGHT RAIN                7     FREEZING RAIN              0
LT FREEZING RAIN          0     HAIL                       0
HEAVY SNOW                0     SNOW                       0
LIGHT SNOW                0     SLEET                      0
FOG                      13     FOG W/VIS <= 1/4 MILE      1
HAZE                      0

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

&&

WASHINGTON DULLES INTERNATIONAL AIRPORT...

THE MONTHLY AVERAGE TEMPERATURE WAS ABOVE NORMAL. MONTHLY
PRECIPITATION WAS WELL BELOW NORMAL.

THE FIRST THIRD OF THE MONTH RANKED AS THE COOLEST START TO
SEPTEMBER ON RECORD. THE PREVIOUS COOLEST START WAS IN 1986.

THE MONTH ENDED WITH 16 CONSECUTIVE DAYS OF NO RAIN (NOT EVEN A
TRACE). THIS IS THE LONGEST STREAK ON RECORD FOR SEPTEMBER.

TWO RECORD DAILY COOL HIGH TEMPERATURES WERE SET LAST MONTH:
A HIGH OF 61 DEGREES ON THE 2ND BROKE THE RECORD OF 70 SET IN 2006.
A HIGH OF 71 DEGREES ON THE 9TH TIED THE RECORD SET IN 1997 AND 1977.

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).

$$

DH/HTS


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