The preliminary statewide average June temperature was 74.4 degrees, 2.2 degrees above the 1991–2020 average and the 18th warmest June on record going back to 1895. The preliminary statewide total June precipitation was 4.15 inches, 0.50 inches below normal and the 52nd wettest June on record statewide.
Data are provisional and may change slightly over time.
Summer Turned on in Late June
June began with largely cooler than normal weather. Daily June temperatures and temperature departures from normal from the long-term station in Normal shows 11 out of the first 15 days of June in Normal were cooler than normal. However, a major pattern change around mid-month brought in much warmer and humid air from the south and southwest. The result was a significant increase in temperatures, such that every day in the latter half of the month was warmer than normal in the town of Normal, many of which were 5 to 12 degrees warmer than normal (Figure 1).
The heat wave in late June was extreme in both its intensity – especially nighttime temperatures – and its duration. High humidity not only pushed afternoon heat index values well above 100 degrees across the state on multiple days, but also kept nighttime temperatures well above normal. The average nighttime low in the last week of June was the highest on record in many places across the Midwest, including in Chicago and Peoria. In fact, the average temperature in Chicago between June 23 and June 30 was similar to the average temperature this time of the year in Orlando, Florida.
The heat wave broke 14 daily high maximum temperature records in Illinois last month, including a 98-degree high temperature in Elizabeth, in the far northwest corner of the state. The warm nights last month broke 88 daily high minimum temperature records in Illinois, including an 80-degree low temperature at Chicago’s O’Hare airport on June 22. All-time June low temperature records were broken in Hoopeston (81 degree low) and Bellevue (78 degree low).
Overall, June average temperatures ranged from the low 70s in northern Illinois to the high 70s in southern Illinois, 2 to 5 degrees above normal (Figure 2). Most places had daytime high temperatures that reached into the low to mid-90s for much of the last 10 days of the month. However, below average temperatures in early June brought in a few sub-50-degree nighttime lows in central and northern Illinois. In this way, June was the epitome of a transition month from spring to summer.
The warmest place in the state last month was Olmsted, Illinois in Pulaski County with an average temperature of 77.3 degrees. The coolest place in the state last month was Barrington in northeast Illinois with an average temperature of 69.9 degrees.
Overall, the preliminary statewide average June temperature was 74.4 degrees, 2.2 degrees above the 1991–2020 average and the 18th warmest June on record going back to 1895.
Variable June Precipitation
June is typically one of the wettest months of the year in Illinois. In some years, June precipitation is consistent across the state, often the case in the wettest of Junes. Last month, however, was more inconsistent. An active storm track across southern Illinois persisted from May into the first two weeks of June, bringing wet weather to much of far southern Illinois. A large ridge established in the eastern U.S. in mid-June, impeding widespread heavy precipitation. Isolated thunderstorms and showers repeatedly popped up, especially in northern Illinois, in the last week of the month; however, most of central and southern Illinois remained on the dry side.
The result of the decidedly variable precipitation last month was a wide range in totals, from less than 3 inches in parts of south-central and east-central Illinois to over 10 inches in southeast Illinois (Figure 3). Most of the state north of highway 13 was near to 2-3 inches drier than normal in June, with the largest departures in the upper Kaskaskia River watershed. Meanwhile, most of far southern Illinois was 1 to 6 inches wetter than normal last month, with the largest departures along the Ohio River.
The wet June weather in far southern Illinois added to what has been a very wet year. Metropolis has already had over 43 inches of precipitation this year, only around 7 inches less than their normal total precipitation for the entire year. Across the river in Paducah, Kentucky, they are having their wettest year to date since 2019, and 7th wettest year to date on record. On the flipside, June was very dry in some pockets of the eastern half of the state, including the 7th driest June on record in Shelbyville and the 3rd driest June in Mowequa.
The preliminary statewide total June precipitation was 4.15 inches, 0.50 inches below normal and the 52nd wettest June on record statewide.
Drought in Illinois
The most June rain fell in places that didn’t really need it, like in far southern Illinois. However, the isolated thunderstorms and showers in late June were beneficial in northern Illinois, especially along and just south of the Wisconsin border. U.S. Drought Monitor maps from the start and end of June show some improvement in northern and western Illinois, thanks to those beneficial showers. The maps also show a slight expansion of abnormal dryness (D0) in east-central Illinois, following a very dry June (Figure 4).
Overall, we enter the agriculturally critical month of July in mostly good shape moisture-wise. However, July often makes or breaks drought in Illinois. Prolonged and dry conditions could accelerate drought impacts to crops, ecosystems, and water supply. However, a July like last year, with abundant rainfall can quickly remove concerns of drought issues. On-the-ground reports of drought conditions and impacts are important sources of information for monitoring as we move into the second half of the growing season. Please consider reporting conditions in your area using the Condition Monitoring Observer Reporting (CMOR) system at: go.illinois.edu/cmor.
Severe Weather
June is one of our most active severe weather months, and last month followed suit. The NOAA Storm Prediction Center preliminary June data includes 26 tornado reports, 82 severe wind reports, and 2 severe hail reports. Among these was an EF-2 tornado that damaged several buildings and trees in Morgan County, and a long-track EF-1 that did damage around and in the Quad Cities. Severe wind was the most common form of severe weather last month, as is often the case. A line of strong storms in the third week of the month caused significant wind damage to buildings and trees across central Illinois, and laid down many acres of corn, although most reports indicate very limited permanent crop damage from these storms. Thankfully, hail was more sparse in Illinois last month.
Illinois has had 130 tornado reports this year between January and June, second only to Texas in the U.S. While the official statewide tornado number isn’t confirmed by National Weather Service later in the year, 2025 has a good shot at breaking the statewide tornado record set just last year.
Outlooks
July is the climatological hottest month of the year in Illinois and can make or break a growing season with its rain (or lack thereof). The latest July outlooks from the Climate Prediction Center continue to show highest chances of warmer than normal weather, with equal chances of above and below normal precipitation (Figure 5). It’s always worth noting that July precipitation often comes in the form of isolated thunderstorms that can produce large differences in totals over small distances.
Similar patterns are in the outlooks for the 3-month period between July and September, indicating a warm last half of summer and start of fall (Figure 6).
