September 2010 Climate Summary

For a printable version of the climate summary which includes more figures, data tables, and state summaries, click here. 

Temperature Summary

September 2010 was cool and wet in the northern portion of the High Plains Region and the southern and western portions of the Region were warm and dry.  Overall, the wet conditions slowed the harvest of row crops; however areas planting winter wheat welcomed the rain.

Average temperatures for the month ranged from 2-6 degrees F (1.1-3.3 degrees C) below normal for most of the Dakotas, were near normal in Nebraska, and generally ranged from 4-6 degrees F (2.2-3.3 degrees C) above normal in much of Colorado, Kansas, and Wyoming.  Central Colorado was particularly warm this month.  High average temperatures, which were up to 9.0 degrees F (5.0 degrees C) above normal, allowed many locations to break into the top 10 warmest Septembers on record.  Colorado Springs, Colorado recorded its warmest September on record with an average temperature of 67.0 degrees F (19.4 degrees C) which was 7.2 degrees F (4.0 degrees C) above normal (period of record 1894-2010).  This broke the old record of 66.6 degrees F (19.2 degrees C) recorded in 1931.

Precipitation Summary

Above normal precipitation was mainly confined to the northern and eastern parts of the High Plains Region this month.  Much of North Dakota, northern and eastern South Dakota, southeastern Nebraska, and eastern Kansas received at least 150 percent of normal precipitation.  The southeastern corner of South Dakota has been extremely wet this year and this month’s wet spot was Brookings 2 NE, South Dakota.  Brookings 2 NE received 8.43 inches (214 mm) of precipitation, or 340 percent of normal precipitation, which broke the old September record of 7.67 inches (195 mm) received in 1986 (period of record 1893-2010).  The total precipitation received at Brookings 2 NE this year now totals 36.80 inches (935 mm) which sets a new record for the entire year!  The previous record was in 2005 with 33.12 inches (841 mm) of precipitation.

Severe weather was still a concern in some areas as hail damage to crops was reported in Nebraska, North Dakota, and Wyoming (source:  National Agricultural Statistics Service).  One storm in eastern Nebraska caused extensive damage on September 13th.  The storm produced baseball sized hail and winds from 80-90 miles per hour (129-145 kilometers per hour).  A University of Nebraska research facility near Mead, Nebraska sustained an estimated $1.5 million in damage as crops were flattened, buildings were damaged, and vehicles were totaled.  

Other areas of the Region received little to no precipitation this month.  The majority of Wyoming, northern and central Colorado, southwestern Kansas, and the panhandle of Nebraska all received precipitation which was only 50 percent of normal or less.  Some locations even received less than 5 percent of normal precipitation.  This month’s dry spot was Boysen Dam, Wyoming which received no precipitation this month and set the record for driest September (period of record 1948-2010).  The old record was 0.02 inches (0.5 mm) received in 1956.

Climate Outlook

La Niña conditions were present across the equatorial Pacific this month and are likely to continue through early 2011.  Like the last 3-month outlook, the temperature outlook indicates a higher probability of above normal temperatures for Colorado, Kansas, the majority of Nebraska, the eastern halves of the Dakotas, and the far southeastern corner of Wyoming.  Equal chances of above, near, or below normal temperatures are predicted elsewhere in the Region.  The precipitation outlook indicates a higher probability of above normal precipitation for northwestern Wyoming.  Meanwhile, the western and southern portions of Colorado have a higher probability of below normal precipitation.  Equal chances of above, near, or below normal precipitation are predicted elsewhere in the Region.  The seasonal outlooks combine the effects of long-term trends, soil moisture, and when applicable, the El Niño Southern Oscillation cycle (ENSO).  More information about these forecasts can be found here.

Drought Watch

Above normal precipitation this month eliminated abnormally dry conditions (D0) in North Dakota, southeastern Nebraska, and northeastern Kansas, and changed the moderate drought conditions (D1) in South Dakota to D0.  However, dry conditions allowed D0 to spread from western Colorado into eastern Colorado, eastern Wyoming, the panhandle of Nebraska, western Kansas, and southwestern South Dakota.  In addition, an area of D1 had developed in central Colorado and extreme southern Wyoming where precipitation deficits were impacting soil moisture along with fall and winter crop decisions.  According to the U.S. Seasonal Drought Outlook released September 16th, the drought conditions in western Wyoming and north central South Dakota were expected to improve through December 2010.