WFO Denver/Boulder

LIMATE REPORT
NATIONAL WEATHER SERVICE BOULDER, CO
150 PM MDT SUN OCT 2 2011

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

...THE DENVER CO CLIMATE SUMMARY FOR THE MONTH OF SEPTEMBER 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              97   09/04/1995
                        09/01/1995
                        09/05/1899
 LOW               17   09/29/1985
HIGHEST            96   09/01        97      -1       96  09/19
LOWEST             38   09/21        17      21       40  09/03
AVG. MAXIMUM     78.6              78.5     0.1     84.8
AVG. MINIMUM     49.9              48.3     1.6     49.1
MEAN             64.2              63.4     0.8     67.0
DAYS MAX >= 90      1               3.4    -2.4        8
DAYS MAX <= 32      0               0.0     0.0        0
DAYS MIN <= 32      0               0.8    -0.8        0
DAYS MIN <= 0       0               0.0     0.0        0

PRECIPITATION (INCHES)
RECORD
 MAXIMUM         4.67   1961
 MINIMUM            T   1892
                        1944
TOTALS           0.89              0.98   -0.09     0.06
DAILY AVG.       0.03              0.03    0.00     0.00
DAYS >= .01         6               6.5    -0.5        3
DAYS >= .10         2               3.3    -1.3        0
DAYS >= .50         1               0.6     0.4        0
DAYS >= 1.00        0               0.1    -0.1        0
GREATEST
 24 HR. TOTAL    0.56   09/14 TO 09/14     09/22 TO 09/22  09/22 TO 09/22
                        09/14 TO 09/15     09/21 TO 09/22

SNOWFALL (INCHES)
RECORDS
 TOTAL            17.2  1971
TOTALS            0.0               1.1

DEGREE_DAYS
HEATING TOTAL      95               125     -30       32
 SINCE 7/1         95               136     -41       35
COOLING TOTAL      78                76       2      100
 SINCE 1/1        941               764     177      862

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

WIND (MPH)
AVERAGE WIND SPEED              8.0
RESULTANT WIND SPEED/DIRECTION   2/206
HIGHEST WIND SPEED/DIRECTION    44/310    DATE  09/02
HIGHEST GUST SPEED/DIRECTION    53/310    DATE  09/02

SKY COVER
POSSIBLE SUNSHINE (PERCENT)   MM
AVERAGE SKY COVER           0.50
NUMBER OF DAYS FAIR           12
NUMBER OF DAYS PC             15
NUMBER OF DAYS CLOUDY          3

AVERAGE RH (PERCENT)     44

WEATHER CONDITIONS. NUMBER OF DAYS WITH
THUNDERSTORM              0     MIXED PRECIP               0
HEAVY RAIN                1     RAIN                       2
LIGHT RAIN                5     FREEZING RAIN              0
LT FREEZING RAIN          0     HAIL                       0
HEAVY SNOW                0     SNOW                       0
LIGHT SNOW                0     SLEET                      0
FOG                       7     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.

$$
...SEPTEMBER 2011 NEAR NORMAL FOR TEMPERATURE AND PRECIPITATION...

THE AVERAGE TEMPERATURE FOR SEPTEMBER WAS 62.4 DEGREES WHICH WAS 0.8
DEGREES ABOVE NORMAL. TEMPERATURES RANGED FROM A HIGH OF 96 DEGREES
ON THE FIRST TO A LOW OF 38 DEGREES ON THE 21ST. SEPTEMBER HAD A
WARM START...WITH A HIGH OF 96 DEGREES AND A MILD LOW TEMPERATURE OF
68 DEGREES ON THE FIRST.  THE 96 DEGREES ON THE FIRST...WAS THE ONLY
DAY THAT MANAGED TO BREAK THE 90 DEGREE MARK FOR THE MONTH. THE 68
DEGREE MORNING LOW SET A NEW RECORD HIGH MINIMUM FOR THAT DATE.
AFTER THE FIRST...THERE WERE NO MORE 90 DEGREE DAYS. HOWEVER..THERE
WERE THREE DAYS...THE 5TH, 26TH AND 28TH WHERE THE TEMPERATURE
REACHED 89 DEGREES. THE ONE 90 DEGREE DAY IN SEPTEMBER BROUGHT THE
SEASONAL TOTAL UP TO 50 DAYS, WHICH IS 11 DAYS SHY OF THE ALL TIME
HIGH OF 61 DAYS BACK IN 2000. THIS PUTS 2011 IN A TIE FOR 9TH PLACE
FOR 90 DEGREE DAYS.

ONLY 0.89 INCHES OF PRECIPITATION FELL AT THE DENVER INTERNATIONAL
AIRPORT IN SEPTEMBER. THIS IS 0.09 INCHES BELOW THE NORMAL OF 0.98
INCHES. SIX DAYS IN SEPTEMBER HAD MEASURABLE PRECIPITATION...WITH
THE GREATEST TWENTY FOUR HOUR PRECIPITATION OF 0.56 INCHES ON THE
14TH. THERE WAS NO SNOWFALL RECORDED DURING THE MONTH...WHICH IS 1.1
INCHES BELOW THE NORM. THE LAST MEASURABLE SNOW RECORDED IN
SEPTEMBER WAS BACK IN 2000 WHEN 0.2 INCHES OF SNOW FELL.

THERE WERE 3 THUNDERSTORMS OBSERVED AT DENVER INTERNATIONAL
AIRPORT DURING THE MONTH. ONLY ONE DAY RECORDED DENSE FOG WITH A
VISIBILITY AT OR BELOW 1/4 MILE. THE PEAK WIND OF 53 MPH FROM A
NORTHWESTERLY DIRECTION OCCURRED ON THE 2ND.

JK


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