June 2019 will be a month remembered for a continuation of above average precipitation and near to seasonably cool temperatures, despite an unseasonably warm finish.
Preliminary data suggest that June 2019 concluded wetter than average, with temperatures slightly below the long-term average. The preliminary average statewide June temperature was 71.0°F, which is 0.9°F below the long-term average. The preliminary average statewide precipitation was 5.39 inches, which is 1.18 inches above the long-term average.
Data are provisional and may change slightly over time
Precipitation and Flooding
After near historic crests at multiple gages along both the Illinois and Mississippi rivers early in the month, water levels continued to slowly recede for many regions heading into July. However, above average precipitation in June, combined with calculated soil moisture content remaining in the 90th to 99th percentile across Illinois, leaves the state with an elevated risk of continued flooding over the next month, especially in regions that may be affected by storms or locally heavy rainfall.
Flooding concerns along Lake Michigan were common in June. According to the U.S. Army Corps of Engineers, water levels in the Lake Michigan-Huron system have risen by nearly 5 inches throughout the month. By the end of June, average levels were reported to be 33 inches, or about 2.75 feet above the historical June average. These levels set a new June record by nearly 2 inches. Water levels of this magnitude haven’t been exceeded since 1986.
Preliminary results show that the June 2019 statewide precipitation total of 5.39 inches was 1.18 inches above the long-term average. This marks the 8th consecutive month in which no part of Illinois has been listed as in drought or abnormally dry by the U.S. Drought Monitor, and the 7th consecutive month with above average statewide precipitation.
June rainfall in Illinois was not evenly distributed. Several regions in the northern half of the state reported precipitation totals slightly below to near average for the month, with localized regions of above average precipitation. A large majority of the southern half of the state experienced more uniform above average precipitation departures, with numerous localities receiving 200 to 300% of normal (see maps below).
A gage near Cobden (Union County) reported the highest official precipitation total for June, with a reading of 10.73 inches.
Preliminary results show that June finished with a statewide average temperature of 71.0°F, which is 0.9°F below the long-term average.
The middle of the month was characterized by an extended period of unseasonably cool temperatures, while the start of astronomical summer brought a steady warming trend which allowed temperatures to reach into the upper 80s and 90s for the final days of June.
Temperature departures for the month were near to 1 to 3° below average, with average temperature values ranging from the mid-60s up into the mid-70s (see maps below).
The highest maximum temperature recorded in the state, at two separate stations, was 97°F, once at a station near Bentley (Hancock County) on June 5, and once at a station near Flora (Clay County) on June 30.
The lowest minimum temperature of only 43°F was reported in Danville (Vermilion County) on the morning of June 14.
July 2019 Outlook
As we head into July, the monthly outlook from the Climate Prediction Center (CPC) favors slight probabilities for below average temperatures across most of the state, as well as continued probabilities of wetter than average conditions statewide.