Here’s the release from the National Weather Service Denver/Boulder. Here’s an excerpt:
THE WINTER MONTHS OF DECEMBER THROUGH MARCH ACROSS NORTHEASTERN COLORADO ARE WIDELY VARIABLE WITH RESPECT TO TEMPERATURE AND SNOWFALL. HISTORICALLY, DECEMBER CAN FREQUENTLY SEE HIGH TEMPERATURES CLIMB INTO THE MILD 60’S WHILE AT TIMES EXPERIENCE VERY COLD TEMPERATURES IN THE MINUS SINGLE DIGITS. ON DECEMBER 21ST, 1983, THE HIGH TEMPERATURE MAXED OUT AT A FRIGID -8 AND IS CURRENTLY DECEMBER’S COLDEST LOW MAXIMUM TEMPERATURE SINCE 1872.
DECEMBER IS TYPICALLY THE FIRST MONTH OF THE WINTER SEASON WHERE EXTREME ARCTIC BLASTS CAN REACH THE EASTERN PLAINS OF COLORADO. SHORT DAYLIGHT HOURS COMBINED WITH THE OCCASIONAL DEEP TROUGH OF LOW PRESSURE CAN USHER IN A FRIGID NORTH CANADIAN AIRMASS INTO THE HIGH PLAINS REGION. DECEMBER CAN ALSO BE CHARACTERIZED AS A MONTH OF HAVING BOTH DRY AND BREEZY BROWN-GROUND CONDITIONS WITH LOW SNOWFALL, WHILE IN OTHER YEARS THE MONTH RECEIVES THE CITIES FIERCEST SNOWSTORMS.
DENVER’S MONTHLY MEAN TEMPERATURE FOR DECEMBER IS 30.0 DEGREES AND IS DENVER’S COLDEST MONTH OF THE YEAR. DECEMBER EDGES SLIGHTLY COLDER THAN JANUARY WHICH HAS A MEAN MONTHLY TEMPERATURE OF 30.7 DEGREES (1981-2010 AVERAGES).
DECEMBER’S DAILY NORMAL HIGH TEMPERATURES HOLD FAIRLY CONSTANT THROUGH THE MONTH STARTING WITH A HIGH OF 45 DEGREES AND ENDING THE MONTH WITH A NORMAL HIGH OF 43 DEGREES. FOR LOW TEMPERATURES, THE MONTH BEGINS WITH A NORMAL LOW OF 19 DEGREES AND FINISHES WITH A LOW OF 17 DEGREES. THE WARMEST TEMPERATURE EVER RECORDED DURING THE MONTH OF DECEMBER, SINCE RECORDS BEGAN IN 1872, WAS 79 DEGREES ON THE 5TH DAY OF THE MONTH, 1939. DECEMBER’S COLDEST TEMPERATURE EVER IN DENVER WAS -25 ON BOTH THE 24TH OF 1876 AND THE 22ND OF 1990…
BEHIND MARCH AND NOVEMBER, DECEMBER IS DENVER’S 3RD SNOWIEST MONTH WITH THE CITY NORMALLY COLLECTING 8.5 INCHES, BASED ON AVERAGES FROM OLD STAPLETON INTL AIRPORT. SIMILAR TO DENVER’S OTHER 3 SNOWIEST MONTHS OF MARCH, APRIL AND NOVEMBER, DECEMBER HAS THE CAPABILITY TO PRODUCE BIG SNOWSTORMS. IN FACT, THE HEAVIEST AND LONGEST DURATION SNOWSTORM IN DENVER’S HISTORY OCCURRED FROM THE 1ST THROUGH THE 5TH OF DECEMBER, 1913. THAT 5 DAY SNOWSTORM DUMPED 45.7 INCHES ON THE YOUNG CITY OF DENVER AND BROUGHT ALL OPERATIONS TO A HALT FOR WEEKS…
AFTER A NOVEMBER 2012 WITH ABOVE NORMAL TEMPERATURES AND BELOW NORMAL PRECIPITATION, THE SAME PATTERN IS EXPECTED TO HOLD THROUGH THE FIRST WEEK OF DECEMBER 2012. THE SHORT TO MEDIUM RANGE MODELS INDICATED A MEAN TROUGH OF COLD LOW PRESSURE DEVELOPING OVER THE NORTHERN AND CENTRAL ROCKIES FROM THE 2ND WEEK THROUGH THE 3RD WEEK. AFTER THE 3RD WEEK OF THE DECEMBER 2012, THE LONG RANGE MODELS INDICATE A BIAS TOWARD ABOVE NORMAL TEMPERATURES WITH NEAR NORMAL PRECIPIATION EXPECTED THROUGH FEBRUARY 2012.