Climatological Report (Monthly)
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000
CXUS56 KSEW 011032
CLMSEA


CLIMATE REPORT
NATIONAL WEATHER SERVICE SEATTLE WA
231 AM PST MON JAN 1 2018

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

...THE SEATTLE-TACOMA WA AIRPORT CLIMATE SUMMARY FOR THE MONTH OF DECEMBER 2017...

CLIMATE NORMAL PERIOD 1981 TO 2010
CLIMATE RECORD PERIOD 1945 TO 2017

WEATHER         OBSERVED          NORMAL  DEPART  LAST YEAR`S
                 VALUE   DATE(S)  VALUE   FROM    VALUE  DATE(S)
                                          NORMAL
................................................................
TEMPERATURE (F)
RECORD
 HIGH              66   12/10/2014
 LOW                6   12/30/1968
HIGHEST            54   12/29        MM      MM       50  12/20
LOWEST             28   12/24        MM      MM       23  12/17
AVG. MAXIMUM     45.5              45.7    -0.2     41.9
AVG. MINIMUM     34.5              35.6    -1.1     34.0
MEAN             40.0              40.6    -0.6     38.0
DAYS MAX >= 90      0               0.0     0.0        0
DAYS MAX <= 32      0               0.8    -0.8        0
DAYS MIN <= 32     10               7.7     2.3       11
DAYS MIN <= 0       0               0.0     0.0        0

PRECIPITATION (INCHES)
RECORD
 MAXIMUM        11.85   1979
 MINIMUM         1.37   1978
TOTALS           5.43              5.35    0.08     3.87
DAILY AVG.       0.18              0.17    0.01     0.12
DAYS >= .01        16              17.6    -1.6       20
DAYS >= .10        10              11.6    -1.6       11
DAYS >= .50         4               3.3     0.7        2
DAYS >= 1.00        2               0.9     1.1        0
GREATEST
 24 HR. TOTAL    1.50   12/29 TO 12/29

SNOWFALL (INCHES)
RECORDS
 TOTAL           22.1   1968
TOTALS            2.6               1.7     0.9      1.0
SINCE 7/1         3.0               2.9     0.1      1.0
SNOWDEPTH AVG.      0                MM      MM        0
DAYS >= 1.0         2                                  0
GREATEST
 SNOW DEPTH         2   12/26                          1
                        12/25
 24 HR TOTAL      1.6   12/24 TO 12/24               0.5

DEGREE_DAYS
HEATING TOTAL     769               755      14      830
 SINCE 7/1       1758              1938    -180     1681
COOLING TOTAL       0                 0       0        0
 SINCE 1/1        392               189     203      291
.................................................................

WIND (MPH)
AVERAGE WIND SPEED              7.8
HIGHEST WIND SPEED/DIRECTION    33/220    DATE  12/29
HIGHEST GUST SPEED/DIRECTION    47/210    DATE  12/29

SKY COVER
POSSIBLE SUNSHINE (PERCENT)   MM
AVERAGE SKY COVER           0.70
NUMBER OF DAYS FAIR            4
NUMBER OF DAYS PC             10
NUMBER OF DAYS CLOUDY         17

AVERAGE RH (PERCENT)     80

WEATHER CONDITIONS. NUMBER OF DAYS WITH
THUNDERSTORM              0     MIXED PRECIP               0
HEAVY RAIN                0     RAIN                       4
LIGHT RAIN               14     FREEZING RAIN              0
LT FREEZING RAIN          0     HAIL                       0
HEAVY SNOW                0     SNOW                       0
LIGHT SNOW                2     SLEET                      0
FOG                      25     FOG W/VIS <= 1/4 MILE      6
HAZE                      0

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

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