Warm and Active June Kicks Off Summer

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 3.39 inches, 1.26 inches below normal and the 46th driest June on record statewide.

Data are provisional and may change slightly over time.

Summer Indeed

June began with relatively mild temperatures across the state, including a few days with average temperatures that were 3 to 10 degrees below normal. However, as daily temperatures and departures from normal in Chicago show in Figure 1, summer heat kicked in mid-month and persisted until the final few days of June. Daily average temperatures between June 13 and June 25 were 5 to 15 degrees above normal in Chicago and statewide.

Figure 1. Daily June average temperatures and departures from normal in Chicago.

The heat wave in mid- to late-June was not particularly extreme in the actual temperatures. Most places in the state reached the mid- to upper-90s several days, and a few places, including Salem and Cahokia Heights, saw high temperatures above 100 degrees. However, these temperatures are not unprecedented for June. However, the heat wave was extreme in how long it lasted, with temperatures 5 to 15 degrees above normal for 10 to 14 consecutive days. For example, Charleston got above 90 degrees on half of the days in June, the most since 1988.

Overall, June average temperatures ranged from the low 70s in northern Illinois to the high 70s in southern Illinois, between 1 and 4 degrees above normal (Figure 2). Most places had daytime high temperatures in the upper 90s and a few places hit or exceeded 100 degrees during the heat wave last month. This included Mt. Vernon, which peaked over 100 degrees for the first time in June since 2012. Meanwhile, many spots in northern Illinois saw nighttime low temperatures dip into the low 40s in early June, including 41 degrees in Lisle and 43 in McHenry. The warmest place in the state last month was Cahokia Heights with an average temperature of 78.3 degrees, and the coolest place in the state in June was Waukegan with an average temperature of 70.2 degrees.

Figure 2. Maps of (left) June average temperature and (right) June average temperature departures from normal.

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.

Dry June for Most but Not All

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. This year however, the dominant weather pattern in the eastern United States was a large and persistent ridge that built up a big high-pressure system over the mid-south and southeast. The result was a persistent parade of storm systems into the Upper Midwest, causing catastrophic flooding in Minnesota, Iowa, and South Dakota, and largely hot and dry conditions in the southeast. As is often the case, Illinois was caught in between these two extremes, and June near to slightly wetter than normal in northern Illinois, and drier than normal in central and southern Illinois (Figure 3).

Figure 3. Maps of (left) June total precipitation and (right) June precipitation departures from normal.

June totals ranged from over 8 inches in East Dubuque to only 0.63 inches in Macomb. In fact, last month was the third driest June on record in Macomb, and the driest since 1991. The preliminary statewide total June precipitation was 3.39 inches, 1.26 inches below normal and the 46th driest June on record statewide.

Drought in Illinois

Illinois was suffering from serious drought this time last year, following extremely dry weather in May and June. By July 1, 2023 93% of the state was in moderate drought and 59% in severe drought. Thankfully, this year we’ve largely avoided serious drought conditions in the state, thanks to abundant (in some cases, surplus) precipitation in April and May. However, the stretches of hot and dry weather last month have begun to quickly deplete soil moisture and drop stream levels in much of central and south-central Illinois. The latest U.S. Drought Monitor map, current as of June 25th, shows around half of the state is abnormally dry, and a small patch of moderate drought along the Indiana border in east-central Illinois (Figure 4).

Figure 4. Maps show the U.S. Drought Monitor from (left) June 25, 2024 and (right) June 27, 2023.

July often makes or breaks drought in Illinois. A continuation of hot and dry conditions could accelerate drought impacts to crops, ecosystems, and water supply. However, a July like last year, with abundant (occasionally, too 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.

Severe Weather

June is one of our most active severe weather months, and while last month was not especially active with severe weather, the northern half of the state was still affected by tornadoes, hail, and severe winds. The NOAA Storm Prediction Center’s preliminary June numbers had 13 tornado reports, including an EF-1 on June 13th that did damage outside of Gibson City in Ford County and four EF-0 tornadoes in the Chicago western suburbs on June 22nd. Strong storms also caused several reports of storm damage from strong winds on June 16th. The airport in Moline recorded 65 mph wind gusts that afternoon.


July is climatologically the 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 above normal temperatures, but have recently leaned closer to near- if not wetter-than normal conditions (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.

Figure 5. Maps show (left) temperature and (right) precipitation outlooks for July.

Meanwhile, outlooks for the three-month period between July and September also show highest chances of above normal temperatures and equal chances of wetter and drier than normal conditions. Concerns of Mississippi River levels in late summer and early fall — something on the minds of many after the last two years — have recently been assuaged by flooding in the Upper Midwest. However, the Ohio Valley is currently dealing with emerging drought conditions, something worth watching as we move into the climatological low-flow season for the big river.

Figure 6. Maps show (left) temperature and (right) precipitation outlooks for July through September.