Justin Glisan, Ph.D.
State Climatologist of Iowa
Iowa Department of Agriculture and Land Stewardship
After a relatively warm and dry mid-summer, rainfall returned to the state during the last weeks of August into early September. Parts of eastern Iowa saw anywhere from 6 to 9 inches above average, producing wet fields and localized flooding. Average temperatures were generally near 2 – 4 degrees F above normal, with southern Iowa warmer than the rest of the state. With the recent widespread rainfall, drought conditions in southern Iowa have shown improvement. As of the second week of September, D0 (Abnormally Dry) conditions covered around 12% of the state. D1 – D2 (Moderate to Severe Drought) covered just under 6% of Iowa. D3 (Extreme Drought) conditions were found mainly in Davis and Appanoose counties.
Increased widespread rainfall over the recent weeks has helped recharge soil moisture profiles, especially in southern Iowa. Lower intensity events allow the rain water to soak into the sub-surface as well as produce run-off into livestock ponds. This rainfall was too late to have an impact on the southern corn crop, but may provide some help to soybeans. Pastures are bouncing back with the possibility of one more cut of hay this year. Fields are wet, so this may delay harvest and field work. Above average temperatures will aid in drying fields.
Warmer than normal conditions are expected to continue across the state during September. The one-month precipitation outlook has been verified to a large degree, with the bulls-eye of above-average rainfall already occurring over the state during the first week of September. The September-October-November outlook indicated temperatures will remain above normal with equal chances of above or below normal precipitation. There is a 60% chance of El Nino during the fall, increasing to a 70% in the winter. Typically, El Nino formation indicates warmer than expected temperatures in Iowa, though more of mixed bag in terms of precipitation.