DES MOINES — August 2020 was the third driest August in 148 years of statewide records despite the Derecho storm event, according to the latest Water Summary Update.
Significant state-wide dryness throughout August caused an expansion of drought conditions, with nearly the entire state rated in some form of dryness or drought. The last United States Drought Monitor depiction for August showed that 99 percent of Iowa was in the D0-D3 category (abnormally dry to extreme drought), which was the largest expanse since August 27, 2013.
"The month of August was the third driest on record for Iowa with barely more than an inch of rain falling,” said Tim Hall, DNR’s coordinator of hydrology resources. “For the summer, the state was short on rainfall by nearly five inches, which means that Iowa has a significant deficit of moisture to make up for this fall."
Precipitation deficits of two to four inches were reported across much of Iowa during August, leading to an intensification and expansion of dryness and drought. Some stations in southeastern Iowa observed deficits of more than four inches. Monthly precipitation totals ranged from 0.11 inch at Salem in Henry County to 5.31 inches at Lake Mills in Winnebago County.
“Widespread rainfall this week should help to improve conditions in September. The current Drought Monitor shows some limited improvement, but the rain that fell after Tuesday morning will be reflected in next week's drought monitor,” Hall said. ”The past several years, September and October have been wet, and a repeat of that pattern will help hydrologic conditions as Iowa heads into the fall months.”
Compared to overall warm conditions in July, temperatures moderated across Iowa in August with a statewide average temperature of 71.9 degrees, 0.4 degrees above normal. August 2020 ties 1921 as the 72nd warmest on record with a warmer August last occurring in 2016.
Streamflow conditions across much of the state are in normal conditions. The Des Moines, Skunk, Raccoon, Chariton, and East Fork 102 River basins have moved into the below normal condition since the last water summary update. Field crews have been out collecting low flow measurements.
For a thorough review of Iowa’s water resource trends, go to www.iowadnr.gov/watersummaryupdate.
The report is prepared by technical staff from Iowa DNR, the Iowa Department of Agriculture and Land Stewardship, IIHR—Hydroscience and Engineering, and the U.S. Geological Survey, in collaboration with Iowa Homeland Security and Emergency Management Department.