South Dakota Climate Summary

July 2011

Nathan Skadsen and Dennis Todey

Synopsis

 Very warm conditions with high dew points were the dominant feature during the month of July.  The high heat indexes (reaching a peak of 125 F) made for very uncomfortable conditions across the whole state, focused mainly on the east, leading to cattle deaths and some potential crop issues.  Precipitation was quite heavy in locations of the northeast, east central and central parts of the state.  Quite dry conditions were not far away in many of these cases as the southeast experienced quite dry conditions along with areas around the Black Hills.

Temperature

 Average temperatures ranged from the low 70’s Fahrenheit in northwestern South Dakota and the Black Hills to the low 80’s in south central South Dakota.  The highest average temperatures were recorded at Pickstown (81°F), Mitchell (80.8°F), and Vermillion 2SE (80.1°F).  The highest temperature seen in the state, 106°F at Cottonwood 2E, was recorded on July 20th.  The lowest average temperatures were recorded at Lead (69.5°F) and Pactola Dam (66.8°F).   The lowest recorded temperature was 44°F seen on July 28^th at the Sioux Falls Weather Forecast Office.

For the first time this year, average temperatures across the state of South Dakota were all above normal.  Many sites in eastern South Dakota experienced a departure from normal temperature greater than 5°F.  The greatest departure from normal temperature was 7.4°F recorded at Hill City.  Other departures from normal temperature across the state can be seen in the following image

Webster in northeast South Dakota will be the hottest on record for July more due to the low temperatures than the high temperatures.  More than 20 other stations had top 15-20 record temperatures.  About 10 stations were in the top 10 warmest, mostly in the southeast part of the state. 

 Precipitation

During the month of July, precipitation across the state varied greatly with areas extreme northeastern and eastern South Dakota receiving more than 8 inches of precipitation while most of the rest of the state saw precipitation values less than 3 inches.  A number of sites, including Timber Lake, McIntosh, Pierre, Highmore, Oelrichs, Eagle Butte, Takini, Caputa, and Gettysburg received less than an inch of precipitation.  An automated station at Britton recorded the most precipitation with 10.1 inches.  Other sites in northeastern South Dakota recording more than 8 inches of precipitation include Columbia 1W, Victor 4NNE, and Roy Lake.  These were all top 10 wettest July’s.   Murdo set a record for the wettest July at 7.26”.

 A few locations came in top 20 driest.  The Rapid City Airport was the 6^th driest on record at 0.66”.

Agricultural Impacts

 July conditions produced some contrasting influences across the state.  The above average temperatures pushed along crop development, which was behind average from the cool-wet spring and early summer.  Usually above average temperatures are not welcomed for corn particularly during July (when tasseling occurs).  The additional development will help catch up some crop development.  But the additional heat may have been taking some toll on yields.  The additional heat may have reduced yield in some cases.  The moist conditions (high dew points) likely helped reduce some stress. 

 Areas of southeast South Dakota have started reporting some dryness impacts.  While the northeast part of the state remained wet, as well as the area around Sioux Falls, locations just south received less than 2” of precipitation during the month.  This led to some reports of firing of corn: 

https://keloland.com/NewsDetail6162.cfm?Id=118801

 The excessive heat seen across the state of South Dakota for parts of July resulted in a number of cattle deaths across the state.  As of July 22^nd, the state veterinarian reported that about 1,700 head of cattle had died due to excessive heat and humidity.  One individual rancher indicated a $900,000 loss on cattle.

Flooding Impacts

 As the month of July progressed, the high water levels on the Missouri River continued to cause problems.  With the high water freeing many logs and other debris, much of the river remained closed to boating and the power plant at Gavins Point Dam was unable to run at full capacity.  The community of Chamberlain continued to fight record river levels as the dike protecting the city became damaged by the high water and waves.  In the community of Dakota Dunes, work continued along the levee as residents were told that they should expect to be out of their homes until fall.  

 Flooding continued to be an issue in many other parts of the state.  Residents near Waubay, SD, did not find any relief from flooding as the area received above average precipitation again this month.  Some residents began to enroll in a FEMA program that provided funds to move buildings out of the flood plain.  Near the community of Roscoe, SD, flooding continued to be a problem as water had nowhere to go.  A stretch of U.S. Highway 12 east of Roscoe was once again closed as water washed away parts of the built up road.  A one-mile section of SD Highway 48 near the South Dakota/Iowa border was closed due to flooding from the Big Sioux River.