You didn’t need to know the statistics to be well aware that August was unusually warm and dry in Thornton and Denver.  The month saw little precipitation and record setting temperatures became commonplace, particularly in the latter half of the month.

For moisture, Denver recorded a mere 0.30 inch in the rain bucket at Denver International Airport.  This was 1.27 inches below the normal of 1.57 inches.  The month barely missed making the list of top 10 driest Augusts by only 0.02 inch.

Afternoon thunderstorms were seen 12 times at DIA but only one brought measurable precipitation.  The storms were typically high-based and yielded little more than wind.

Thornton followed DIA’s lead with little precipitation as we only saw 0.27 inch during the month.

Temperatures were the real weather story for August 2011 as rather than seeing cooler temperatures through the month like normal, the mercury stayed exceedingly high.

Overall DIA saw an average temperature of 77.0 degrees making it the hottest August on record.  This surpassed the previous record August from 1937 when 76.8 degrees was seen.  The month also went into the record books as the sixth warmest month ever recorded in Denver.

Temperatures ranged from a high of 99 degrees on the 25th down to a low of 55 degrees on the 20th.  Through August 31st, Denver had seen 71 consecutive days of 80 degrees or warmer weather.  This easily bested the previous longest streak of 59 days set in 2002.

Seven individual temperature records were set during the month.  These included a tied record high on the 18th of 98 degrees last set in 1986; the 23rd tied the record high of 98; the 24th set a new record high for the date of 98 degrees; the 25th set a new record high of 99 degrees; the 28th set a record high of 96 degrees; the 28th saw a record high minimum of 67 degrees; the 31st tied the record high of 98 degrees.

Here in Thornton we were certainly hot but not nearly as much so as DIA.  We recorded an average temperature of 74 degrees.  Our warmest reading was 96.2 degrees and our coolest was 54.  In all we saw 20 days with temperatures of 90 degrees or warmer.

While the high temperatures were notable, DIA benefits from later arrival of the typical afternoon thunderstorms due to its location further east of the rest of Denver.  This certainly aided in the airport recording higher temperatures than anywhere else in the metro area.  For more on that story, check out the Denver Weather Examiner.

Below are the official Denver weather statistics for August 2011.  Click here to view Thornton’s August 2011 climate summary.

CLIMATE REPORT...CORRECTED
NATIONAL WEATHER SERVICE BOULDER, CO
430 PM MDT FRI SEP 2 2011

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

...THE DENVER CO CLIMATE SUMMARY FOR THE MONTH OF AUGUST 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             105   08/08/1878
 LOW               40   08/26/1910
                        08/25/1910
                        08/24/1910
HIGHEST            99   08/25       105      -6       97  08/22
LOWEST             55   08/20        40      15       47  08/17
AVG. MAXIMUM     92.7              87.2     5.5     88.6
AVG. MINIMUM     61.3              57.9     3.4     59.0
MEAN             77.0              72.5     4.5     73.8
DAYS MAX >= 90     22              11.5    10.5       12
DAYS MAX <= 32      0               0.0     0.0        0
DAYS MIN <= 32      0               0.0     0.0        0
DAYS MIN <= 0       0               0.0     0.0        0

PRECIPITATION (INCHES)

RECORD 
 MAXIMUM         5.85   1979  
 MINIMUM         0.02   1924
TOTALS           0.30              1.57   -1.27     1.05
DAILY AVG.       0.01              0.05   -0.04     0.03
DAYS >= .01         3               8.6    -5.6        6
DAYS >= .10         1               4.3    -3.3        3
DAYS >= .50         0               1.2    -1.2        1
DAYS >= 1.00        0               0.3    -0.3        0
GREATEST
 24 HR. TOTAL    0.27   08/03 TO 08/03   0.68  08/01/10 TO 08/01/10

SNOWFALL (INCHES)
RECORDS
 TOTAL            0.0   NO SNOW EVER RECORDED IN AUGUST
TOTALS            0.0   NO SNOW EVER RECORDED IN AUGUST         

DEGREE_DAYS
HEATING TOTAL       0                 5      -5        0
 SINCE 7/1          0                11     -11        3
COOLING TOTAL     382               244     138      280
 SINCE 1/1        863               688     175      762              

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

WIND (MPH)
AVERAGE WIND SPEED              8.8
RESULTANT WIND SPEED/DIRECTION   3/202
HIGHEST WIND SPEED/DIRECTION    39/180  DATE  08/31  38/190 08/12
HIGHEST GUST SPEED/DIRECTION    48/200  DATE  08/31  45/340 08/12
                                                            08/16
SKY COVER
POSSIBLE SUNSHINE (PERCENT)   MM (NO LONGER RECORDED)
AVERAGE SKY COVER           0.50
NUMBER OF DAYS FAIR            4
NUMBER OF DAYS PC             26
NUMBER OF DAYS CLOUDY          1

AVERAGE RH (PERCENT)     41

WEATHER CONDITIONS. NUMBER OF DAYS WITH
THUNDERSTORM              0     MIXED PRECIP               0
HEAVY RAIN                1     RAIN                       1
LIGHT RAIN                8     FREEZING RAIN              0
LT FREEZING RAIN          0     HAIL                       0
HEAVY SNOW                0     SNOW                       0
LIGHT SNOW                0     SLEET                      0
FOG                       4     FOG W/VIS <= 1/4 MILE      1
HAZE                      5                                           

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

As summer vacations wind down and families prepare to send their kids back to school in August, Colorado weather also starts to settle down. The chances for severe weather decrease markedly during August and by the end of the month daytime temperatures are dropping quite a bit as well.

At the start of the month Denver usually averages around 88 degrees for a high temperature. By the end of August that drops to 82 degrees. Similarly, nighttime lows drop from 60 to 53 from the start to the end of the month. Generally clear skies can be expected between midnight and noon but the afternoon often brings showers and thunderstorms. These storms typically develop over the foothills then bring precipitation to the Denver metro area.

Despite that moisture, the chance for severe weather decreases considerably compared to the first two months of summer. Cooler air near the surface helps to create a stable atmosphere thus keeping thunderstorms from usually becoming too intense. After the middle of August, tornadoes and damaging hail are pretty rare. The slow movement of storms this time of year are more likely to produce potentially heavy rain.

Click here to read the complete preview including a look back at what was a record setting month last year.