Tag: drought

The preliminary statewide average October temperature was 59.6 degrees, 4.8 degrees above the 1991-2020 average and tied for 9^th warmest on record going back to 1895. The preliminary statewide total October precipitation was 2.61 inches, 0.65 inches below the 1991-2020 average and the 67^th driest on record.  

Data are provisional and may change slightly over time.

Mild October Temperatures

October is the most quintessential fall month, weather-wise, as we transition from a more summer-like September to what is often a more winter-like November. This year, October played to type and moved from summer-like warmth in the first half to real fall days in the second half. Temperature departures from normal in Olney show daily average temperatures in the first half of the month regularly reached into the 70s, between 8 and 12 degrees above normal. A cool down around October 20^th pushed most of the rest of the month’s temperatures slightly cooler than normal (Figure 1).

October average temperatures ranged from the high 50s in northern Illinois to the mid-60s in southern Illinois, between 2 and 7 degrees above average (Figure 2). High temperatures regularly reached into the high 80s and low 90s in early October, including 93 degrees in Minonk and 92 in Charleston. However, low humidity helped nighttime temperatures dip into the 20s and 30s on m any nights, including 26 degrees in Moline and 31 in Mt. Vernon.

The coolest point in the state last month was Barrington in Lake County at 55.1 degrees, and the warmest point was Morrisonville in Christian County at 64.1 degrees. Last month was a top 10 warmest October on record in several places, including Champaign-Urbana (6^th warmest). Unusually high temperatures in early October broke 28 daily high maximum temperature records and 7 daily high minimum temperature records. Two places, McHenry and Normal, broke all-time October high maximum temperature records with highs of 90 and 92 degrees, respectively, in the first week of the month. Only 1 daily low minimum temperature record was broken last month.

Overall, the preliminary statewide average October temperature was 59.6 degrees, 4.8 degrees above the 1991-2020 average and tied for 9th warmest on record going back to 1895.

Dry North, Wet South… Again

October precipitation has a strange perception in Illinois, especially for agriculture. While our soils and streams usually need a good drink of water coming out of the summer, too much rain can delay harvest, winter wheat and cover crop planting, and other necessary fall fieldwork. This year, though, October rain was mostly not an issue because (1) harvest progressed very quickly and (2) rain was hard to come by north of Interstate 70.

The first half of October was quite dry and extended drought conditions statewide from September. A significant weather pattern shift that coincided with the mid-month cooldown brought more frequent and substantial rain, especially in southern Illinois. Overall, October total precipitation ranged from around 0.90 inches in western Illinois to over 6 inches in parts of southern and south-central Illinois. Most of the state south of Interstate 70 was 1 to 4 inches wetter than normal in October, while most of central and northern Illinois were 1 to 3 inches drier than normal (Figure 3).

Overall, the preliminary statewide total October precipitation was 2.61 inches, 0.65 inches below the 1991-2020 average and the 67^th driest on record

Drought Continues in Central Illinois, Improves in Southern Illinois

Below normal rainfall continued from August and September into October in central and northern Illinois. Most of central Illinois has been 5 to 10 inches drier than normal since August 1^st, less than 50% of normal over that time. The dry weather helped harvest progress very quickly, but also created some challenges with dry vegetation and high fire risk. Dozens of field fires were reported across the state in the first two weeks of October, including one that burned over 1,000 acres in north-central Illinois. Many rivers and streams remain at or near low-flow, including extremely low levels on the Sangamon and Vermilion Rivers.

In contrast, drought was eased or altogether broken in much of southern Illinois, thanks to abundant rainfall in October. The U.S. Drought Monitor released on October 28^th showed significant drought improvement in southern Illinois, including many places that went from severe drought (D2) in the beginning of the month to abnormal dryness (D0) at month’s end (Figure 4).

Outlooks

month of the year can bring all four seasons, including tornadoes touching down on ground with some snowpack. Quintessential November weather, though, is infinite thick clouds… break out the crock pot.

The latest outlooks from the Climate Prediction Center lean to a warmer than normal November across Illinois, but equal chances of wetter and drier than normal weather (Figure 5). A wet November would be something to be thankful for, to help with drought.

Outlooks for the period from November to January continues to lean warmer than normal, but we start to see better chances of wetter than normal conditions as we move into the heart of winter.

Below normal rainfall has continued into fall and has both expanded and worsened drought conditions across the state. Dry vegetation and crops have caused dozens of field fires over the past two weeks. Multiple rivers have hit low- or no-flow, including the Sangamon and Vermilion, and some municipalities have begun to enact voluntary water conservation measures. The short-term forecast shows dry weather will likely persist through mid-October, and longer outlooks do not show strong signs of substantially wetter weather through at least the end of October.

Drought Intensifies as the 2025-26 Water Year Begins

Very dry weather in August, September, and the first week of October caused a significant expansion and intensification of drought across Illinois. The October 7^th edition of the U.S. Drought Monitor shows at least moderate drought in 86% of the state, severe drought in 43% of the state, and a small area of extreme drought in east-central Illinois.

Maps in Figure 1 show much of central and northern Illinois were 8 to 15 inches drier than normal for the 2024-25 water year (October 1, 2024 – September 30, 2025), and parts of east-central Illinois have been 10 to 13 inches drier than normal in the 2025 calendar year.

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 have caused very low levels along many of our state’s rivers, including the Sangamon, Vermilion, Embarras, Kaskaskia, and the Illinois River.

Very low levels and flow along the Sangamon River have added to dry and warm weather to cause several central Illinois lakes and reservoirs to drop quickly. As of October 9^th, Lake Decatur was 2.4 feet below the normal level and the City of Decatur has requested voluntary water conservation as the lake continues to drop.

Fire and Dust Risk

Recent rain has helped reduce field fire risk in many places. However, fire risk remains somewhat to very high, especially in central Illinois. We saw dozens of field fires across the state over the past two weeks, illustrating the continued fire risk. 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.

Where are We Headed?

The October 7 edition of the U.S. Drought Monitor has over 86% of the state in at least moderate drought, which is up from just 6% of the state in late August. The Drought Monitor also has extreme drought (D3) in east-central Illinois for the first time since 2012.

Unfortunately, the next 7-days look to be dry once again across most of the state (Figure 3). Despite the recent unusually warm weather, the seasons work in our favor now, because our average temperatures will drop as we continue through fall and into winter, which will at least limit evaporation from streams and lakes. Climate Prediction Center outlooks for the third week of October show a return to unusually warm weather, with no strong signal of wetter weather in sight.

In summary: we expect drought conditions across the state will likely continue to worsen in coming weeks, albeit at a slower rate because of cooler weather and some beneficial rainfall in far southern Illinois.