Climatological Report (Monthly)
Issued by NWS Denver/Boulder, CO

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CXUS55 KBOU 011355
CLMDEN

CLIMATE REPORT
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
645 AM MST MON JAN 1 2018

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

...THE DENVER CO CLIMATE SUMMARY FOR THE MONTH OF DECEMBER 2017...

CLIMATE NORMAL PERIOD 1981 TO 2010
CLIMATE RECORD PERIOD 1872 TO 2017

WEATHER         OBSERVED          NORMAL  DEPART  LAST YEAR`S
                 VALUE   DATE(S)  VALUE   FROM    VALUE  DATE(S)
                                          NORMAL
................................................................
TEMPERATURE (F)
RECORD
 HIGH              79   12/05/1939
 LOW              -25   12/22/1990
                        12/24/1876
HIGHEST            69   12/12        62       7       65  12/30
LOWEST             -4   12/24        -4       0      -15  12/17
AVG. MAXIMUM     48.3              42.8     5.5     42.7
AVG. MINIMUM     18.0              17.1     0.9     12.9
MEAN             33.2              30.0     3.2     27.8
DAYS MAX >= 90      0               0.0     0.0        0
DAYS MAX <= 32      4               5.8    -1.8        6
DAYS MIN <= 32     28              29.4    -1.4       30
DAYS MIN <= 0       1               2.0    -1.0        4

PRECIPITATION (INCHES)
RECORD
 MAXIMUM         5.21   1913
 MINIMUM         0.00   1881
TOTALS           0.21              0.35   -0.14     0.78
DAILY AVG.       0.01              0.01    0.00     0.03
DAYS >= .01         4               4.1    -0.1        6
DAYS >= .10         1               1.1    -0.1        2
DAYS >= .50         0               0.1    -0.1        0
DAYS >= 1.00        0               0.0     0.0        0
GREATEST
 24 HR. TOTAL    0.10   12/23 TO 12/23
 STORM TOTAL     0.10   12/23 TO 12/23

SNOWFALL (INCHES)
RECORDS
 TOTAL           57.4   1913
TOTALS            4.0   2017        8.5

DEGREE_DAYS
HEATING TOTAL     979              1086    -107     1146
 SINCE 7/1       2150              2468    -318     2042
COOLING TOTAL       0                 0       0        0
 SINCE 1/1        881               769     112      878

FREEZE DATES
RECORD
 EARLIEST     09/08/1962
 LATEST       06/08/2007
EARLIEST                        10/07
LATEST                          05/05
.................................................................

WIND (MPH)
AVERAGE WIND SPEED              10.0
RESULTANT WIND SPEED/DIRECTION   2/214
HIGHEST WIND SPEED/DIRECTION    37/270    DATE  12/04
HIGHEST GUST SPEED/DIRECTION    48/280    DATE  12/04

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          5

AVERAGE RH (PERCENT)          49

WEATHER CONDITIONS. NUMBER OF DAYS WITH
FOG OR MIST                   12
FOG VSBY LESS 1/4 MI           4
THUNDER                        0
ICE PELLETS                    0
HAIL                           0
FREEZING RAIN DRIZZLE          0
DUST STORM                     0
SMOKE OR HAZE                  5
BLOWING SNOW                   0
TORNADO                        0

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

...DECEMBER 2017...WARM START...COLD FINISH...

WITH MUCH OF NOVEMBER 2017 SPEND UNDER A DOMINANT DRY AND STABLE
RIDGE OF HIGH PRESSURE OVER THE SOUTHWEST UNITED STATES, THE SAME
PATTERN PERSISTED INTO THE MIDDLE OF DECEMBER. WITH THE STRENGTH OF
THE RIDGE PEAKING IN THE SECOND WEEK OF THE MONTH, A RECORD HIGH
TEMPERATURE RECORD WAS SET IN DENVER ON THE 12TH WITH A HIGH
TEMPERATURE OF 69 DEGREES. THIS ENDED UP BEING THE HIGHEST
TEMPERATURE FOR THE MONTH. A SHIFT IN THE NORTH AMERICAN WEATHER
PATTERN BEGAN TO DEVELOP ON THE 19TH AND 20TH AND WAS FELT STATEWIDE
EARLY ON THE 21ST WITH THE PASSAGE OF AN ARCTIC SURFACE COLD FRONT
AND ASSOCIATED STORM SYSTEM ALOFT. THIS BROUGHT SNOWFALL TO THE
REGION WITH 2.3 INCHES OFFICIALLY AT DENVER AHEAD OF THE CHRISTMAS
HOLIDAY. THIS ALSO BROUGH THE COLDEST TEMPERATURE OF THE MONTH WITH
A LOW OF -4 DEGREES ON THE MORNING OF THE 24ND.

AFTER THE CHRISTMAS HOLIDAY, COLD TEMPERATURES PERSISTED ACROSS ALL
OF THE NORTHERN, CENTRAL AND EASTERN UNITED STATES INCUDING
NORTHEAST COLORADO. WITH TEMPERATURES HOLDING WELL BELOW THE
SEASONAL AVERAGE FOR THE LAST 10 DAYS OF THE MONTH, THIS BROUGHT THE
MONTHLY AVERAGE TEMPERATURE CLOSER TO THE NORMAL OF 30.0 DEGREES.
THE MONTH ENDED WITH A FINAL AVERAGE OF 33.2 OFFICIALLY FOR DENVER.

TEMPERATURES:

THE AVERAGE TEMPERATURE AT DENVER INTERNATIONAL AIRPORT FOR THE
MONTH WAS 33.2 DEGREES F, WHICH IS 3.2 DEGREES ABOVE NORMAL. THE
WARMEST DECEMBER ON RECORD OCCURRED IN 1933 WITH AN AVERAGE MONTHLY
TEMPERATURE OF 43.8 DEGREES F. THE COLDEST DECEMBER ON RECORD WAS
OCCURRED IN 1983 WITH A MONTHLY AVERGAE OF 17.4 DEGREES.

TEN WARMEST DECEMBER`S IN DENVER WEATHER HISTORY SINCE 1872:

43.8 1933
41.2 1980
40.9 1939
40.5 1889
39.7 1906
39.6 1946
39.5 1957, 1881
39.2 1890
38.8 1896

TEN COLDEST DECEMBER`S IN DENVER WEATHER HISTORY SINCE 1872:

17.4 1983
21.2 1909
22.1 1878
22.7 1873
23.1 1913
23.7 1932
24.1 2009
24.3 1914
24.6 1978
24.8 1884

PRECIPITATION:

DECEMBER 2017 LANDED SHY OF THE MONTHLY AVERAGE COMING IN WITH 0.21
INCHES. THIS HIGHEST AMOUNT WAS RECEIVED FROM THE COLD STORM SYSTEM
OF THE 23RD WHERE THE STORM BROUGH 0.10" TO DENVER. A SECOND BUT
WEAK STORM SYSTEM AFTER THE CHRISTMAS HOLIDAY, BROUGHT ADDITIONAL
MOISTURE OF 0.01 INCH. BY THE END OF THE YEAR, DECEMBER ENDED THE
MONTH WITH 0.21 INCHES, WHICH IS 0.14 BELOW THE NORMAL OF 0.35
INCHES.

TEN WETTEST DECEMBER`S IN DENVER WEATHER HISTORY SINCE 1872:

5.21 INCHES 1913
2.84 INCHES 1973
2.34 INCHES 1892
2.32 INCHES 1883
1.70 INCHES 1876
1.56 INCHES 1891
1.50 INCHES 1960
1.42 INCHES 1924
1.40 INCHES 1918
1.32 INCHES 1892

TEN DRIEST DECEMBER`S IN DENVER WEATHER HISTORY SINCE 1872:

0.00 1881
   T 1905
0.01 INCHES 1916, 1895
0.03 INCHES 1977, 1931
0.04 INCHES 2004, 1890
0.05 INCHES 2002, 1995

NO THUNDER THUNDER WAS OBSERVED AT DENVER INTERNATIONAL AIRPORT AND
4 DAYS WITH DENSE FOG WITH A VISIBILITY AT OR BELOW 1/4 MILE DURING
THE MONTH. THE PEAK WIND GUST OF 48 MPH FROM THE NORTHWEST OCCURRED
ON THE 4TH.

$$


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