August precipitation was well-below normal in the Missouri River Basin, particularly in the western and far northern portions, which received less than 25% of normal precipitation. The lack of precipitation and dry soil conditions resulted in 74% of average August runoff in the Missouri River Basin above Sioux City, Iowa (upper Basin). The 2020 calendar year forecast for the upper Basin, updated on September 1, is 30.6 million acre-feet (MAF), 119% of average. Average annual runoff for the upper Basin is 25.8 MAF. Runoff in the upper Basin during the remainder of 2020 is forecast to be below average.