Climatological Report (Monthly)
Issued by NWS Boise, ID

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CXUS55 KBOI 021259
CLMBOI

CLIMATE REPORT
NATIONAL WEATHER SERVICE BOISE ID
550 AM MST WED JAN 2 2019

THE AVERAGE TEMPERATURE FOR DECEMBER WAS SLIGHTLY WARMER THAN
NORMAL, ALTHOUGH THE MONTH STARTED OUT COLD, WITH THE TEMPERATURE
STAYING BELOW FREEZING FROM THE 5TH THROUGH THE 8TH. THE REST OF THE
MONTH WAS RELATIVELY MILD, WITH DAILY AVERAGES NEAR OR ABOVE NORMAL.
THE 16TH THROUGH THE 20TH WAS THE WARMEST PERIOD, WITH DAILY
AVERAGES IN THE LOWER 40S, AND OVERNIGHT LOWS ABOVE FREEZING FROM
THE 17TH THROUGH THE 19TH.

PRECIPITATION WAS NEAR NORMAL, BUT TOTAL SNOWFALL WAS SLIGHTLY BELOW
NORMAL. HALF OF THE TOTAL PRECIPITATION FELL ON THE FIRST TWO DAYS
OF THE MONTH, WHEN A DEEP UPPER LEVEL TROUGH FROM THE NORTH PACIFIC
CROSSED THE AREA. AT THE AIRPORT 3.8 INCHES OF SNOW FELL, RESULTING
IN 3 INCHES ON THE GROUND BY THE MORNING OF THE 3RD.

THE TROUGH BROUGHT COLD AIR, WHICH WAS MADE EVEN COLDER DURING
NIGHTTIME HOURS, DUE TO MAINLY CLEAR SKIES AND SNOW COVER WHICH ALSO
INHIBITED DAYTIME WARMING.

MILDER WEATHER ARRIVED ON THE 9TH AS THE UPPER LEVEL FLOW SHIFTED
INTO THE WEST. ALONG WITH THE WARMER AIR, THE WESTERLY WINDS CARRIED
A SERIES OF PACIFIC WEATHER SYSTEMS INLAND. MOST PROVIDED ONLY LIGHT
PRECIPITATION AND BREEZY SOUTHEAST TO SOUTHWEST WINDS. ON THE 17TH
AND 18TH TWO CLOSELY SPACED SYSTEMS BROUGHT NEARLY A THIRD OF AN
INCH OF RAIN.

LIGHT SNOW FELL ON THE 23RD AND 29TH, BUT MOST OF IT MELTED IN
RESPONSE TO AFTERNOON TEMPERATURES IN THE UPPER 30S AND LOWER 40S.

ON THE 31ST NORTHERLY FLOW, FOLLOWING AN UPPER LEVEL TROUGH FROM THE
GULF OF ALASKA, BROUGHT ONLY SLIGHT COOLING, BUT NOTICEABLY COLDER
WIND CHILL TEMPERATURES.

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

...THE BOISE ID CLIMATE SUMMARY FOR THE MONTH OF DECEMBER 2018...

CLIMATE NORMAL PERIOD 1981 TO 2010
CLIMATE RECORD PERIOD 1875 TO 2019

WEATHER         OBSERVED          NORMAL  DEPART  LAST YEAR`S
                 VALUE   DATE(S)  VALUE   FROM    VALUE
                                          NORMAL
.............................................................
TEMPERATURE (F)
HIGHEST            51   12/20
LOWEST             11   12/06
AVG. MAXIMUM     38.9              37.5     1.4
AVG. MINIMUM     26.3              24.0     2.3
MEAN             32.6              30.7     1.9
DAYS MAX >= 90      0
DAYS MAX <= 32      5
DAYS MIN <= 32     27
DAYS MIN <= 0       0

PRECIPITATION (INCHES)
RECORD
 MAXIMUM         5.96   1871
TOTALS           1.40              1.55   -0.15
DAYS >= .01        13
DAYS >= .10         5
DAYS >= .50         0
DAYS >= 1.00        0
GREATEST
 24 HR. TOTAL    0.48   12/01 TO 12/02

SNOWFALL (INCHES)
TOTALS            4.9
SINCE 7/1         4.9
GREATEST
 SNOW DEPTH         3   12/03
 24 HR TOTAL      3.5   12/01 TO 12/02

DEGREE_DAYS
HEATING TOTAL     997              1061     -64     1120
 SINCE 7/1       2201              2315    -114
COOLING TOTAL       0                 0       0        0
 SINCE 1/1       1121               942     179
..............................................................

WIND (MPH)
AVERAGE WIND SPEED              7.6
RESULTANT WIND SPEED/DIRECTION   3/142
HIGHEST WIND SPEED/DIRECTION    32/130    DATE  12/14
HIGHEST GUST SPEED/DIRECTION    43/210    DATE  12/16

SKY COVER
POSSIBLE SUNSHINE (PERCENT)   MM

AVERAGE RH (PERCENT)     73


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

$$


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