An extremely dry end to summer and start to fall has intensified ongoing drought in central and southern Illinois and increased the fire and blowing dust risk as we approach harvest. River levels have dropped near or below low stage, including on the Kaskaskia, Sangamon, and Mackinaw, among others.
Dry August Sparks Flash Drought
August was extremely dry in much of southern and south-central Illinois, including in the western reaches of the St. Louis Metro east area where virtually no rain fell (Figure 1). The extreme dryness and mid-month heat ushered in rapid onset or “flash” drought in southern Illinois, rapidly drying soils and vegetation. The quick dryness has been quite a contrast to the extremely wet spring southern Illinois experienced. In fact, 2025 has been a top 20 wettest year on record through August in several counties including Lawrence and Massac, despite the recent intense drought (Figure 1).
In east-central Illinois, the dry August only added to what has been an extremely dry year. 2025 to date has been the 12th driest on record in Champaign County, 7 inches below normal, and has been the driest year to date in Champaign-Urbana since 1988.
Root zone soil moisture has been depleted because of the below normal rainfall (Figure 2). Soil moisture at 4 inch and 8 inch depths at the Illinois Climate Network station in Brownstown has quickly declined well below the wilting point and level of severe drought over the last month. This soil moisture decline has occurred following an extremely heavy rain event in July where the station picked up more than 5 inches of rain in less than 12 hours.
The combination of dryness and mid-August heat has also sped up crop dry down and likely affected some yields in the driest parts of the state. Water table levels have also dropped across the southern half of the state as soil moisture is depleted. Water table levels at the State Water Survey’s WARM station in Peoria dropped more than 5 feet between July 1 and September 1 (data available here: https://stateclimatologist.web.illinois.edu/data/current-illinois-water-table-levels/).
Low River Levels Across the Midwest
Drought usually affects the flow and level of small streams and creeks first, then the tributaries of our larger rivers. When dry conditions persist for weeks to months we can see low flow along our larger rivers. Persistently dry conditions this year in east-central Illinois have caused very low levels along the Kaskaskia River, Sangamon River, and Vermilion River. We are also beginning to see very low levels along the Mackinaw River in central Illinois, and the South Fork River in southeast Illinois. Wetter weather in the Upper Midwest has kept the Mississippi River at or above normal stage so far, and the Illinois River flow has been helped by a wet August in Wisconsin and northern Illinois. So, for now, navigation issues on the big rivers are abated.
Where are We Headed?
The September 11 edition of the U.S. Drought Monitor has over 30% of Illinois at least moderate drought (Figure 3). Most of the drought issues remain in the southern half to two-thirds of the state.
Unfortunately, the next 7-days look absolutely bone dry across our drought areas (Figure 4). Meanwhile, rising temperatures will put an end to our glorious cool weather, and add to drought stress. Multiple days with high temperatures in the upper 80s to low 90s and low humidity will significantly accelerate drought in southern and central Illinois, including adding to crop and vegetation stress or senescence, further dry soils, and lower pond and stream levels. Climate Prediction Center outlooks for the third week of September show the warmer weather will likely stick around but give us a small glimmer of hope with near normal precipitation. That said, mid- to late-September is typically not a wet time. In summary: drought conditions in southern and central Illinois will get worse before they get better.
Fire and Dust Risk
Harvest is going this week and will likely be in full swing by mid-September. The dry weather has quickly dried corn and beans, and combined with low humidity and dry topsoil, has increased field and grass fires across the Midwest. Extra precautions should be taken ahead of, during, and after harvest to ensure everyone stays safe considering the enhanced fire risk. You can find more information on farm fire safety here: go.illinois.edu/farmfiresafety.
Additionally, the dry crop and topsoil increase the chances of blowing dust on dry and windy days. Folks should consider weather conditions and the potential dust created when harvesting. We want to avoid dangerous blowing dust situations like what we saw this spring.