A Statistical Preview of Denver's October Weather

         ...A STATISTICAL PREVIEW OF DENVER'S OCTOBER WEATHER...

CLIMATOLOGICALLY, AFTER FAIRLY STABLE TEMPERATURE VARIATION DURING THE WARMEST MONTHS OF JULY AND AUGUST, TEMPERATURE SPREADS ACROSS THE MONTH OF SEPTEMBER BEGIN TO WIDEN AS DRYER AND COOLER AIR FROM THE NORTHERN PLAINS AND CANADIAN REGION PERIODICALLY WORK THEIR WAY INTO THE HIGH PLAINS OF EASTERN COLORADO BEHIND PASSING STORM SYSTEMS TO THE NORTH. DURING THE MONTH OF OCTOBER IN DENVER, TEMPERATURE SPREADS CAN WIDEN EVEN FURTHER AS THE REGION TRULY MOVES OUT OF THE WARM MONTHS FOR GOOD.

DENVER'S MONTHLY MEAN TEMPERATURE FOR OCTOBER IS 50.9 DEGREES (1981-2010 AVERAGES) AND IS DENVER'S FIFTH WARMEST MONTH OF THE YEAR BEHIND JULY, AUGUST, JUNE AND MAY RESPECTIVELY. THE MONTH STARTS WITH A NORMAL HIGH OF 72 DEGREES AND ENDS WITH A NORMAL HIGH OF 59 DEGREES. FOR LOW TEMPERATURES, THE MONTH BEGINS WITH A NORMAL OF 42 DEGREES AND TRENDS BELOW THE FREEZING MARK TO FINISH WITH A NORMAL OF 31.

THE WARMEST TEMPERATURE EVER RECORDED DURING THE MONTH OF OCTOBER, SINCE RECORDS BEGAN IN 1872, WAS 90 DEGREES AND OCCURRED ON THE FIRST DAY ON THE MONTH WAY BACK IN 1892. THIS IS ALSO THE LATEST 90 DEGREE OR HIGHER TEMPERATURE DENVER HAS RECORDED. THE COLDEST TEMPERATURE EVER RECORDED IN DENVER FOR OCTOBER WAS A FRIGID -2 DEGREES AND OCCURRED ON THE 29TH DAY OF 1917.

OCTOBER: DENVER'S TOP 10 WARMEST (MEAN TEMPERATURES):

59.9 DEGREES 1950

57.9         1963

57.9         1934

57.4         1933

57.0         1947

56.3         1875

55.9         1956

55.9         1940

55.9         1938

55.9         1921

OCTOBER: DENVER'S TOP 10 COLDEST (MEAN TEMPERATURES):

38.9 DEGREES 1969

42.9         2009

43.3         1925

44.0         2002

44.3         1923

44.7         1984

45.9         1970

46.3         1877

46.5         1919

46.5         1913

OCTOBER: DENVER'S 10 WETTEST

4.17 INCHES 1969

3.92        1892

3.72        1942

3.50        1923

3.47        1984

3.05        1914

3.03        2007

2.84        1947

2.62        1957

2.46        1960

OCTOBER: DENVER'S 10 DRIEST

   T INCHES 1934

0.01        1933

0.05        1962

0.05        1944

0.06        1988

0.06        1954

0.06        1948

0.08        2003

0.08        2001

0.10        1980

ALTHOUGH SEPTEMBER IS THE FIRST MONTH OF THE SNOW SEASON IN DENVER, OCTOBER IS THE MONTH WHEN DENVER AND THE ENTIRE FRONT RANGE BEGIN TO SEE THE STRONG LIKELIHOOD OF COLD PACIFIC STORM SYSTEMS BRINGING THE SEASON'S FIRST REAL SNOWFALL. SINCE SNOW MEASURING BEGAN IN DENVER IN 1882, MONTHLY SNOW TOTALS OF GREATER THAN 0.1" HAS OCCURRED 101 TIMES WITH 16 YEARS RECEIVING A TRACE AND ANOTHER 16 YEARS MISSING OUT ENTIRELY FROM ANY SNOW.

OCTOBER: DENVER`S 10 SNOWIEST

31.2 INCHES 1969

22.7        1906

22.1        1997

17.8        1923

17.2        2009

16.4        1897

16.2        1929

14.0        1889

13.8        1905

13.6        1908

OCTOBER: DENVER'S LEAST 10 SNOWIEST

 0.0  16 OCCURRENCES

   T  16 OCCURRENCES

                    ...THE OUTLOOK FOR OCTOBER 2015...

AFTER A SEPTEMBER OF RECORD WARMTH ACROSS THE REGION AND BELOW NORMAL PRECIPITATION, THE CLIMATE PREDICTION CENTER’S SHORT RANGE, 8 TO 14 DAY OUTLOOK, CALLS FOR A CONTIUATION OF ABOVE NORMAL TEMPERATURES OVER THE WESTERN UNITED STATES, INCLUDING EASTERN COLORADO. PRECIPITATION IS EXPECTED TO BE NEAR SEASONAL NORMALS WITH A SLIGHT BIAS TO BEING WETTER DURING THIS PERIOD. BEYOND MID-OCTOBER, THE DOMINANT RIDGE OF HIGH PRESSURE, WHICH HAS PERSISTED OVER THE WESTERN UNITED STATES FROM MID-SUMMER THROUGH CURRENT, IS EXPECTED TO WEAKEN. AS THE MOUNTIAN WEST REGION TRENDS TOWARD A MORE PROGRESSIVE PATTERN OF FREQUENT TROUGHS OF LOW PRESSURE, TEMPERATURES ARE EXPECTED TO MODERATE COOLER TO NEAR SEASONAL NORMALS WITH PRECIPITATION EXPECTED TO BE NEAR NORMAL AS WELL.

         ...OCTOBER STATISTICS...

...TEMPERATURES (1981-2010 NORMALS)...

AVERAGE HIGH...........................  65.3

AVERAGE LOW............................  36.6

MONTHLY MEAN...........................  50.9

DAYS WITH HIGH 90 OR ABOVE.............   0 (<0.1)

DAYS WITH HIGH 32 OR BELOW.............   0 (0.4)

DAYS WITH LOW 32 OR BELOW..............   9 (8.5)

DAYS WITH LOWS ZERO OR BELOW...........   0 (<0.1)

...PRECIPITATION...

MONTHLY MEAN...........................   1.02 INCHES

DAYS WITH MEASURABLE PRECIPITATION.....   5 (5.3)

AVERAGE SNOWFALL.......................   4.0 INCHES

...MISCELLANEOUS OCTOBER AVERAGES...

HEATING DEGREE DAYS.................... 440

COOLING DEGREE DAYS....................   5

WIND SPEED (MPH).......................   7.8*

WIND DIRECTION......................... SOUTH*

DAYS WITH THUNDERSTORMS................   1* (0.8)

DAYS WITH DENSE FOG....................   1* (0.6)

PERCENT OF SUNSHINE....................  72*

(NOTE: SUNSHINE DATA ARE NO LONGER COLLECTED AS OF OCTOBER 1, 2009)

* = 1971-2002 NORMALS

...OCTOBER EXTREMES...

RECORD HIGH............................  90 DEGREES ON 10/1/1892

RECORD LOW.............................  -2 DEGREES ON 10/29/1917

WARMEST................................  59.9 DEGREES IN 1950

MAXIMUM COOLING DEGREE DAYS............  14 IN 2006, 2005

MINIMUM COOLING DEGREE DAYS............   0 NUMEROUS (23) YEARS

COLDEST................................  39.0 DEGREES IN 1969

MAXIMUM HEATING DEGREE DAYS............ 801 IN 1969

MINIMUM HEATING DEGREE DAYS............ 159 IN 1950

WETTEST................................   4.17 INCHES IN 1969

DRIEST................................. TRACE IN 1934

SNOWIEST...............................  31.2 INCHES 1969

LEAST SNOWY............................   0.0 INCHES NUMEROUS YEARS (16)

WFO BOULDER