Wildfires and record-setting temperatures provided a clue as to what the highlights of September’s weather would be and with the month over we now see it in the statistics. September 2010 will go down in the record books as not only one of the driest Septembers on record but also one of the warmest.
A mere 0.06 inch of precipitation was recorded at the official monitoring station at Denver International Airport over the month. Most of that fell during a four-day period from the 18th to the 22nd and in the end 25 days had no moisture at all. That scarcity of precipitation allowed the month to finish in a tie with 1882 and 1920 for the 5th driest September on record. Here in Thornton we fared a bit better having recorded 0.09 inch of precipitation but that paltry difference is not hardly worth noting.
Not only was precipitation in short supply, so too were even clouds. Zero days were reported as cloudy, 10 days as partly cloudy and 20 days were fair (sunny). Thornton recorded over 200 hours of sunshine for the month – more than any other month in 2010.
Temperatures were well above normal for the month and into top 10 status as well. The average temperature of 67.0 degrees was 4.6 degrees above normal. This puts September 2010 in a tie with 1939 as the seventh warmest September on record. Thornton was thankfully quite a bit cool as we recorded an average temperature of 64.7 degrees.
Four record high temperatures were tied or broken during the month. On the 19th a scorching 96 degrees was recorded easily besting the old record for the date of 93 degrees last set in 1980. That also was the hottest temperature ever recorded that late in the season. Other dates this past month setting records were: 94 on the 20th beating the old record of 92 last set in 1956; tied the record on the 26th with 1892; 92 on the 28th topping the old record of 89 last set in 1994.
In all the month recorded eight 90 degree days, well above the normal of 2 for September. An amazing 25 days had temperature at or above 80 degrees which is the highest number of 80 degree temperatures in September since 1872. Overall temperatures ranged from the high of 96 on the 19th down to a low of 40 on the 3rd. Thornton’s temperatures ranged from a high of 93.6 on the 19th to a low of 40.7 degrees on the 7th.
Looking beyond the statistics, the most noteworthy events of September 2010 were the wildfires in the foothills west of Denver. The Fourmile Canyon Fire northwest of Boulder became the most destructive in state history in terms of the number of homes destroyed. West of Loveland the Reservoir Road Fire claimed homes as well but was thankfully controlled relatively quickly due to the quick response of firefighters.
What does the October 2010 weather hold for Denver and the Colorado Front Range? Right now the dry and warm weather is expected to continue. Get all the details in our October 2010 preview.
From the National Weather Service:
...THE DENVER CO CLIMATE SUMMARY FOR THE MONTH OF SEPTEMBER 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 97 09/04/1995
09/01/1995
09/04/1960
09/05/1899
LOW 17 09/29/1985
HIGHEST 96 09/19 97 -1 91 09/01
LOWEST 40 09/03 17 23 36 09/28
AVG. MAXIMUM 84.8 77.4 7.4 78.0
AVG. MINIMUM 49.1 47.3 1.8 48.9
MEAN 67.0 62.4 4.6 63.5
DAYS MAX >= 90 8 2.2 5.8 1
DAYS MAX <= 32 0 0.2 -0.2 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 0.06 1.14 -1.08 0.74
DAILY AVG. T 0.04 -0.04 0.02
DAYS >= .01 3 6.3 -3.3 5
DAYS >= .10 0 MM MM 4
DAYS >= .50 0 MM MM 0
DAYS >= 1.00 0 MM MM 0
GREATEST
24 HR. TOTAL 0.03 09/22 TO 09/22 0.42 09/22 TO 09/23
SNOWFALL (INCHES)
RECORDS
TOTAL 17.2 1971
TOTALS 0.0 2.1 0.0
DEGREE_DAYS
HEATING TOTAL 32 136 -104 117
SINCE 7/1 35 146 -111 139
COOLING TOTAL 100 57 43 78
SINCE 1/1 862 696 166 533
FREEZE DATES
RECORD
EARLIEST 09/08/1962
LATEST 06/08/2007
EARLIEST 10/07
LATEST 05/05
.................................................................
WIND (MPH)
AVERAGE WIND SPEED 9.3 9.2
RESULTANT WIND SPEED/DIRECTION 2/190
HIGHEST WIND SPEED/DIRECTION 37/310 09/06 36/210 09/30
HIGHEST GUST SPEED/DIRECTION 44/320 09/06 45/280 09/30
SKY COVER
POSSIBLE SUNSHINE (PERCENT) MM
NUMBER OF DAYS FAIR 20
NUMBER OF DAYS PC 10
NUMBER OF DAYS CLOUDY 0
AVERAGE RH (PERCENT) 36
WEATHER CONDITIONS. NUMBER OF DAYS WITH
THUNDERSTORM 3 MIXED PRECIP 0
HEAVY RAIN 0 RAIN 0
LIGHT RAIN 4 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 2
HAZE 2
- INDICATES NEGATIVE NUMBERS.
R INDICATES RECORD WAS SET OR TIED.
MM INDICATES DATA IS MISSING.
T INDICATES TRACE AMOUNT.