Historically July is a pretty busy month in terms of weather as thunderstorms are very common.  July 2011 lived up to the month’s reputation as the middle of the month saw a seemingly endless stream of heavy, wet thunderstorms.  This was followed by a string of 90 degree and warmer days that approached record setting territory.

The big story for the month was the precipitation as there was a lot of it.  DIA saw sixteen thunderstorms during July, five more than normal.  The official Denver monitoring at the airport recorded 3.41 inches of rain which was well above the normal of 2.16 inches.  The measurement fell just shy of making the list of top 10 wettest July’s on record.

The station at DIA however lived up to its reputation as under-reporting rainfall as compared to locations closer to downtown.  In fact, a station the old Stapleton site recorded 6.54 inches.  Here in Thornton 5.51 inches fell into our rain bucket.

• What is up with the weather records at DIA?  Click here for more about how the station at the airport is causing problems with Denver’s climate records.

One precipitation record was set during the month when 1.03 inches of rain fell on the 13th.  This easily bested the previous 24 hour record for the date of 0.45 inch set in 1993.

Temperatures for the month were considerably above normal but fell short of ‘top 10’ status.  The average temperature for the month, as recorded at DIA, was 75.9 degrees.  This was 2.5 degrees above the normal of 73.4.

The warmest temperature of the month occurred on the Fourth of July when the mercury climbed to 99 degrees.  On the opposite end, 56 degrees on the 1st of the month was the coldest reading.

In all, 20 days saw temperatures at or above 90 degrees during July 2011; five more than normal.  July 15th started a string of 18 consecutive days of 90 degree or warmer high temperatures.  That streak will go into the books as tying for the second longest in history.

Thornton, like most other places in the metro area, was not near as warm.  Our average temperature was 73.8 degrees, right near normal.  Our warmest temperature occurred on the 4th as well and matched Denver’s mark of 99 degrees.  The mercury dipped to 53.6 degrees on the 1st and was our coldest temperature.

Click here to view Thornton’s July 2011 climate summary

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

CLIMATE NORMAL PERIOD 1971 TO 2000
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   07/20/2005
 LOW               42   07/04/1903
                        07/31/1873
HIGHEST            99   07/31       105      -6      102  07/17
                        07/04
LOWEST             56   07/01        42      14       53  07/09
                                                          07/05
                                                          07/04
AVG. MAXIMUM     91.1              88.0     3.1     89.3
AVG. MINIMUM     60.7              58.7     2.0     59.5
MEAN             75.9              73.4     2.5     74.4
DAYS MAX >= 90     20              15.0     5.0       18
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         6.41   1965
  MINIMUM         0.01   1901
TOTALS           3.41              2.16    1.25     3.70
DAILY AVG.       0.11              0.07    0.04     0.12
DAYS >= .01        11               9.3     1.7       13
DAYS >= .10         7                MM      MM        5
DAYS >= .50         2                MM      MM        2
DAYS >= 1.00        2                MM      MM        2
GREATEST
 24 HR. TOTAL    1.08  07/12 TO 07/13  1.84 07/04/10 TO 07/04/10       

SNOWFALL (INCHES)
RECORDS
 TOTAL            0.0   NONE EVER RECORDED IN JULY
TOTALS            0.0                0.0                              

DEGREE_DAYS
HEATING TOTAL       0                 1      -1        3
 SINCE 7/1          0                 1      -1        3
COOLING TOTAL     346               261      85      303
 SINCE 1/1        481               422      59      482              

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

WIND (MPH)
AVERAGE WIND SPEED              9.5                  9.1
RESULTANT WIND SPEED/DIRECTION   3/181               MM
HIGHEST WIND SPEED/DIRECTION    51/210 DATE  07/13  41 07/30/10
HIGHEST GUST SPEED/DIRECTION    68/300 DATE  07/14  48 07/30/10

SKY COVER
POSSIBLE SUNSHINE (PERCENT)   MM
AVERAGE SKY COVER           0.50
NUMBER OF DAYS FAIR            6
NUMBER OF DAYS PC             22
NUMBER OF DAYS CLOUDY          3

AVERAGE RH (PERCENT)     50

WEATHER CONDITIONS. NUMBER OF DAYS WITH
THUNDERSTORM              0     MIXED PRECIP               0
HEAVY RAIN                4     RAIN                       6
LIGHT RAIN               17     FREEZING RAIN              0
LT FREEZING RAIN          0     HAIL                       4
HEAVY SNOW                0     SNOW                       0
LIGHT SNOW                0     SLEET                      0
FOG                       5     FOG W/VIS <= 1/4 MILE      0
HAZE                      4                                           

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