October 2011 started out quite warm but then stabilized into a seasonal pattern.  As is often the case with Colorado weather though, at one point we went from record high temperatures to snow in a span of two days.

In terms of temperature, Denver finished the month with an overall overage temperature of 52.6 degrees.  This was 1.6 degrees above the normal for the month of 50.9 degrees.  Temperatures ranged from a high of 87 degrees on the first of the month down to 14 degrees on the 26th and 27th.

Here in Thornton we were slightly cooler with an average temperature of 50.4 degrees.  Our highs ranged from a top mark of 86.6 degrees on the first down to a very cold 12.8 degrees on the 27th.

Two record high temperatures were tied or broken during the month.  On the 15th, the mercury climbed to 82 degrees which tied the record for the date last set in 1938.  On the 24th the temperature hit 80 degrees, breaking the previous record high for the date of 79.

Quite a bit more precipitation was recorded than normal during October 2011.  1.79 inches fell into the rain bucket at DIA which is 0.82 inch above normal.  Much of that precipitation fell on October 8th when 1.04 inches was recorded, a record for the date.  DIA also recorded a trace of snowfall, the first of the season.

The Mile High City was hit with its first snowstorm on the 25th and 26th when 8.5 inches of the white stuff fell.  That also was the snowfall total for the month which far exceeded the normal of 4.2 inches.

Thornton nearly mirrored Denver’s precipitation as we recorded 1.75 inches during the month between rain and snowmelt.  Our snowfall fell short of DIAs however as we recorded 6.6 inches during the storm late in the month.

Click here to view Thornton’s climate summary for October 2011.

From the National Weather Service:

...THE DENVER CO CLIMATE SUMMARY FOR THE MONTH OF OCTOBER 2011... 

CLIMATE NORMAL PERIOD 1981 TO 2010
CLIMATE RECORD PERIOD 1872 TO 2011

WEATHER         OBSERVED          NORMAL  DEPART  LAST YEAR`S
                 VALUE   DATE(S)  VALUE   FROM    VALUE  DATE(S)
                                          NORMAL
................................................................
TEMPERATURE (F)
RECORD
 HIGH              90   10/01/1892
 LOW               -2   10/29/1917
HIGHEST            87   10/01        90      -3       85  10/03
LOWEST             14   10/26        -2      16       20  10/28
                        10/27
AVG. MAXIMUM     67.3              65.3     2.0     69.7
AVG. MINIMUM     37.9              36.6     1.3     40.9
MEAN             52.6              50.9     1.7     55.3
DAYS MAX >= 90      0               0.0     0.0        0
DAYS MAX = .01         4               5.3    -1.3        4
DAYS >= .10         3               2.4     0.6        2
DAYS >= .50         1               0.5     0.5        0
DAYS >= 1.00        1               0.1     0.9        0
GREATEST
 24 HR. TOTAL    1.04   10/08 TO 10/08

SNOWFALL (INCHES)
RECORDS
 TOTAL           31.2   1969
TOTALS            8.5                4.2

DEGREE_DAYS
HEATING TOTAL     400               438     -38      300
 SINCE 7/1        495               576     -81      335
COOLING TOTAL      23                 5      18        8
 SINCE 1/1        964               769     195      870

FREEZE DATES
RECORD
 EARLIEST     09/08/1962
 LATEST       06/08/2007
EARLIEST      10/17             10/07
LATEST                          05/05
................................................... 

WIND (MPH)
AVERAGE WIND SPEED              9.8
RESULTANT WIND SPEED/DIRECTION   4/205
HIGHEST WIND SPEED/DIRECTION    49/210    DATE  10/06
HIGHEST GUST SPEED/DIRECTION    63/200    DATE  10/06

SKY COVER
POSSIBLE SUNSHINE (PERCENT)   MM
AVERAGE SKY COVER           0.40
NUMBER OF DAYS FAIR           13
NUMBER OF DAYS PC             15
NUMBER OF DAYS CLOUDY          3

AVERAGE RH (PERCENT)     44

WEATHER CONDITIONS. NUMBER OF DAYS WITH
THUNDERSTORM              1     MIXED PRECIP               0
HEAVY RAIN                0     RAIN                       1
LIGHT RAIN                5     FREEZING RAIN              0
LT FREEZING RAIN          0     HAIL                       0
HEAVY SNOW                1     SNOW                       2
LIGHT SNOW                3     SLEET                      0
FOG                       5     FOG W/VIS

Following on what was a “top 10” warmest and driest September, October tried to follow suit but fell short of achieving record status.  Nevertheless, the month was considerably warmer and drier than normal. 

In terms of temperature the month ranked as the 11th warmest fall just 0.1 degree short of top 10 status.  The average temperature was 55.3 degrees; a considerable 4.3 degrees above normal.  Temperatures ranged from a high of 85 degrees on the 3rd down to a low of 20 on the 28th.  In all there were only two days when the mercury dipped to freezing or below; seven days below the normal nine we receive. 

Thornton was quite a bit cooler overall than Denver as we had an average temperature of 52.7 degrees.  Highs ranged from 84 degrees on the 4th down to 23.3 degrees on the 28th. 

As an interesting side note, it was just last October that we had our second coldest October on record.  The average temperature in October 2009 was a chilly 42.9 degrees and we had 17 days with temperatures at or below freezing! 

We suffered through another dry month which did spark a couple of wildfires.  A mere 0.54 inch of precipitation was recorded at the official monitoring site at Denver International Airport.  This was just barely more than half of the normal of 0.99 inch.  Most of the precipitation fell in the form of rain on the 12th when 0.34 inch was recorded.  Here in Thornton we were a bit wetter having recorded 0.73 inch of precipitation during the month. 

For the first time since 2003 no snow was recorded in Denver in October.  This is only the 15th time since 1882 that has happened.  On average we expect to receive 4.1 inches of the white stuff. 

See the official statistical summary from the National Weather Service below for more details.  Click here to view the monthly climate summary for Thornton.

CLIMATE REPORT
NATIONAL WEATHER SERVICE BOULDER, CO
205 PM MDT MON NOV 1 2010

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

...THE DENVER CO CLIMATE SUMMARY FOR THE MONTH OF OCTOBER 2010...

CLIMATE NORMAL PERIOD 1971 TO 2000
CLIMATE RECORD PERIOD 1872 TO 2010

WEATHER         OBSERVED          NORMAL  DEPART  LAST YEAR'S
                 VALUE   DATE(S)  VALUE   FROM    VALUE  DATE(S)
                                          NORMAL
................................................................
TEMPERATURE (F)
RECORD
 HIGH              90   10/01/1892
 LOW               -2   10/29/1917
HIGHEST            85   10/03        90      -5       84  10/18
LOWEST             20   10/28        -2      22       17  10/10
AVG. MAXIMUM     69.7              66.0     3.7     54.7
AVG. MINIMUM     40.9              35.9     5.0     31.1
MEAN             55.3              51.0     4.3     42.9
DAYS MAX >= 90      0               0.0     0.0        0
DAYS MAX <= 32      0               0.3    -0.3        3
DAYS MIN <= 32      2               8.6    -6.6       17
DAYS MIN <= 0       0               0.0     0.0        0

PRECIPITATION (INCHES) 
RECORD
  MAXIMUM         4.17   1969  
  MINIMUM            T   1934
TOTALS           0.54              0.99   -0.45     1.36
DAILY AVG.       0.02              0.03   -0.01     0.04
DAYS >= .01         4               5.3    -1.3        8
DAYS >= .10         2                MM      MM        5
DAYS >= .50         0                MM      MM        0
DAYS >= 1.00        0                MM      MM        0
GREATEST
 24 HR. TOTAL    0.34   10/12 TO 10/12     0.39  10/20 TO 10/21       

SNOWFALL (INCHES)
RECORDS
 TOTAL           31.2   1969
TOTALS            0.0               4.1    -4.1       17.2             

DEGREE_DAYS
HEATING TOTAL     300               436    -136      676
 SINCE 7/1        335               582    -247      815
COOLING TOTAL       8                 0       8        0
 SINCE 1/1        870               696     174      533              

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

WIND (MPH)
AVERAGE WIND SPEED              9.1               9.6
RESULTANT WIND SPEED/DIRECTION   3/231            MM
HIGHEST WIND SPEED/DIRECTION    41/350  10/25    37/350  10/29/09
HIGHEST GUST SPEED/DIRECTION    51/350  10/25    54/200  10/05/09

SKY COVER
POSSIBLE SUNSHINE (PERCENT)   MM                                      

NUMBER OF DAYS FAIR            9
NUMBER OF DAYS PC             22
NUMBER OF DAYS CLOUDY          0

AVERAGE RH (PERCENT)     44

WEATHER CONDITIONS. NUMBER OF DAYS WITH
THUNDERSTORM              4     MIXED PRECIP               0
HEAVY RAIN                0     RAIN                       3
LIGHT RAIN                5     FREEZING RAIN              0
LT FREEZING RAIN          0     HAIL                       0
HEAVY SNOW                0     SNOW                       0
LIGHT SNOW                0     SLEET                      0
FOG                       2     FOG W/VIS <= 1/4 MILE      1
HAZE                      7                                           

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

With the first full month of fall here, October usually brings one of the quietest weather months in the Denver area with plenty of mild, sunny days and clear, cool nights.  Certainly given our recent trend of well-above normal temperatures many are hoping for some relief. 

The month actually has our second highest amount of sunshine with 72 percent with September having the most with 74 percent. Interestingly enough, the month following, November, is one of the lowest sunshine months with only 64 percent.

Typically October brings our first real taste of winter with the first freeze on average coming on the 7th of the month and the first snow on the 15th of the month.

You can get all the details including a look back at historical October weather and a look ahead at what October 2010 is expected to bring in our complete preview here.