Illinois farmers are experiencing two different weather extremes this year. Northern Illinois is dry, with rainfall that's 3 to 5 inches below normal. Southern Illinois is wet, with more than twice the average rainfall.
Meanwhile, the dust storms that blanketed the northern half of the state in mid-May were the worst since the 1930s Dust Bowl, CBS News Chicago meteorologist David Yeomans says.
The shifts in both average and severe weather patterns that meteorologists have warned about for years are happening, and they're impacting Illinois ag in big ways.
Changes in weather patterns
Starting with current weather patterns, Yeomans points to two trends he already sees happening:
1. It's getting warmer. Yeomans says the average temperature is rising over time. Take Peoria, Ill., for example. From 1970 to 2024, the average temperature during the summer increased by 2.7 degrees F. Although the average temperature variation depends on the area, including warmer temperatures in bigger cities, temperatures are going up on average.
2. Freeze windows are getting smaller. Freeze windows are getting smaller, starting later in the fall and ending earlier in the spring. That means the growing season is getting longer. Yeomans says that in Rockford, Ill., from 1920 to 1950, the average first freeze in the fall was on Oct. 5, and the average last freeze was on May 5. But from 1990 to 2020, the first freeze in the fall was on Oct. 15, and the last freeze was on April 26.
Illinois state climatologist Trent Ford adds that freezes can only be tracked with temperatures, and temperature isn't the best indicator for frost damage. Although a freeze occurs between 28 and 32 degrees, Ford says, "We can get damaging frost to newly emerged soybeans or corn when it's only 35 or 36 degrees as a low."
This number isn't always exact and is dependent on the humidity level, topography, stage of the crop and amount of moisture. Ford notes that freeze windows are important for long-term planning, but they aren't as helpful for year-to-year planning.
Future weather predictions
Overall, Yeomans and Ford say Illinois farmers can look for more heat, more tornadoes and more extremes in the future. Here are some predictions:
1. Warmer and drier summer. Right now, the world is in a phase between El Niño and La Niña, called ENSO-neutral. Ford describes these as phases of the El Niño Southern Oscillation, which is determined by sea surface temperatures in the Pacific Ocean.
Although rainfall and temperature are only one factor, historical data says that the 2025 summer might be warmer and drier than an average summer.
For example, Yeomans says the average temperature from all summers between 1991 and 2020 in Rockford, Ill., is 71.7 degrees with an average of 13.22 inches of rain. Looking at data from ESNO-neutral summers specifically, the average temperature is 72.5 degrees, with 11.68 inches of rain.
Yeomans also notes that "dry weather begets dry weather in summer." That's because in areas that are already dry at this point, there's less moisture evaporating from the soil.
2. More severe weather. The tornado alley is shifting eastward into Illinois, Yeomans says. Look for more tornadoes in the Upper Midwest or Deep South, including in Illinois, and fewer in Texas and Oklahoma.
Ford says to look for an increase in not only tornadoes, but also damaging thunderstorm winds and hail. Tornadoes get all the attention, but Ford says hail and wind cause much more economic damage each year.
"The increase in crop insurance rates that pretty much everybody is seeing across the Midwest, that is not a tornado thing, that is a hail issue," Ford says.
Plus, hail and strong winds often cause more widespread damage, affecting multiple counties or fields at a time.
The favorable conditions for tornadoes, hail and thunderstorms include warmer conditions and higher humidity levels, which result in more instability. And the right conditions could create more shear.
"We can expect in the future we may see a slight uptick in the frequency of hail and wind events in the Midwest and Midsouth," Ford says.
3. One extreme or the other. Yeomans notes that according to the Fifth National Climate Assessment, a U.S. government report on climate change, weather changes will impact agriculture. These changes include:
Too much spring rain. Southern Illinois farmers can attest to excessive spring rains this year, causing planting delays. Ford says that wet springs can also make it hard for farmers to apply preemergence herbicides, leading to weed control problems.
Flood then drought. Yeomans says the National Climate Assessment is seeing more rapid transitions between flood and then flash drought. "It doesn't rain for maybe three weeks, and it's 90 or 100 degrees and soil dries out quickly," he describes. Ford says he sees a lot of maladaptation to wetter springs through field tiling. "We put in field tiles and unless those are controlled tiling, it works really well to lower the water table during the spring, but when you need a higher water table to keep those crops going in the summer, it's working against you because those tiles are draining those fields," he says.
Warmer summer. Ford notes that although temperatures are warming during the summer, they are especially rising in the evenings, leading to warmer nights across the Midwest, which can affect crops during pollination. Ford says rising temperatures can affect crops, but they can also be harmful to livestock.
Winters are warmer, too, and their impact on ag is often overlooked. Ford says those warmer winters allow insects, disease and weeds to overwinter.
"Winters are warming at a much faster rate than all other seasons, and that's across the region from Southern Illinois all the way to northern Michigan," Ford says.
