Climatological Report (Monthly)
Issued by NWS Sterling, VA

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CXUS51 KLWX 012130 RRA
CLMDCA

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

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

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

CLIMATE NORMAL PERIOD 1981 TO 2010
CLIMATE RECORD PERIOD 1871 TO 2017

WEATHER         OBSERVED          NORMAL  DEPART  LAST YEAR`S
                 VALUE   DATE(S)  VALUE   FROM    VALUE
                                          NORMAL
.............................................................
TEMPERATURE (F)
RECORD
 HIGH             104   09/07/1881
 LOW               36   09/23/1904
HIGHEST            92   09/24        92       0
LOWEST             53   09/10        48       5
AVG. MAXIMUM     80.8              79.5     1.3       MM
AVG. MINIMUM     64.2              62.4     1.8       MM
MEAN             72.5              71.0     1.5
DAYS MAX >= 90      3               2.4     0.6
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        17.45   1934
 MINIMUM         0.11   2005
TOTALS           1.43              3.72   -2.29       MM
DAILY AVG.       0.05              0.12   -0.07
DAYS >= .01         4               8.3    -4.3
DAYS >= .10         2               5.5    -3.5
DAYS >= .50         2               2.4    -0.4
DAYS >= 1.00        0               1.0    -1.0
GREATEST
 24 HR. TOTAL    0.77   09/02 TO 09/02

DEGREE_DAYS
HEATING TOTAL       6                24     -18       MM
 SINCE 7/1          6                24     -18       MM
COOLING TOTAL     241               202      39       MM
 SINCE 1/1       1732              1513     219       MM
..............................................................

WIND (MPH)
AVERAGE WIND SPEED              7.5
HIGHEST WIND SPEED/DIRECTION    24/010    DATE  09/30
HIGHEST GUST SPEED/DIRECTION    31/340    DATE  09/30

SKY COVER
POSSIBLE SUNSHINE (PERCENT)   MM
AVERAGE SKY COVER           0.60
NUMBER OF DAYS FAIR            5
NUMBER OF DAYS PC             18
NUMBER OF DAYS CLOUDY          7

AVERAGE RH (PERCENT)     69

WEATHER CONDITIONS. NUMBER OF DAYS WITH
THUNDERSTORM              1     MIXED PRECIP               0
HEAVY RAIN                2     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                       7     FOG W/VIS <= 1/4 MILE      0
HAZE                      0

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

&&

WASHINGTON DC...RONALD REAGAN WASHINGTON NATIONAL AIRPORT...

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

THIS WAS THE 8TH STRAIGHT WARMER THAN NORMAL SEPTEMBER.

DESPITE THE ABOVE NORMAL MONTHLY AVERAGE TEMPERATURE, THE FIRST
THIRD OF THE MONTH RANKED AS THE COOLEST START TO SEPTEMBER SINCE
1986.

THE MONTH ENDED WITH 16 CONSECUTIVE DAYS OF NO RAIN (NOT EVEN A
TRACE). THIS IS THE 3RD LONGEST STREAK ON RECORD FOR SEPTEMBER.

CLIMATE RECORDS HAVE BEEN KEPT AT RONALD REAGAN WASHINGTON NATIONAL
AIRPORT SINCE AUGUST OF 1941. ADDITIONAL TEMPERATURE RECORDS FOR THE
WASHINGTON DC AREA OBSERVED DOWNTOWN EXTEND BACK TO JANUARY OF 1872.
PRECIPITATION RECORDS EXTEND BACK TO JANUARY OF 1871. SNOWFALL
RECORDS BEGAN IN JANUARY OF 1884.

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

$$

DH/HTS


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