Hottest summer ever in Chicago
Northern Illinois suffers drought conditions as southern half of state gets a soaking
The beaches remained closed in Chicago due to the pandemic, even as the city recorded its hottest summer ever. (Facebook/The Magnificent Mile)
By Ted Cox
It was a tale of two states this summer, as Chicago recorded its hottest season ever and northern Illinois endured drought conditions, while the southern half of Illinois got above-average rainfall.
Those looking for evidence of climate change can examine Chicago. The National Weather Service reported Tuesday that the city recorded its hottest meteorological summer ever from June through August, with a mean temperature of 76.7 degrees, beating the previous record of 76.4 set in 1955 and almost five degrees above normal.
It wasn’t a case of record heat waves, but simply a sustained summer of warmer-than-normal temperatures. According to the weather service, Chicago set only one daily record for high temperature, right at the beginning of summer on June 2, with a reading of 94 degrees. But “the average high temperature for the summer season was 86.2 degrees, which is 4.3 degrees above the 1981-to-2010 average. The average low temperature was 67.1 degrees, which is 5.4 degrees above normal.”
It was the sixth-hottest June on record in the city, the fourth-warmest July, and the sixth-warmest August.
With all the heat and sunshine, the city measured 7.8 inches of precipitation, 4.3 inches below normal.
In fact, near-drought conditions extended across the northern half of the state, according to a summer recap released Wednesday by Illinois State Climatologist Trent Ford. He cited U.S. Drought Monitor data showing that almost the entire northern half of the state was considered “abnormally dry” at the end of August, with DuPage County and a swath running inland from the Mississippi River south of the Quad Cities considered to be in a moderate drought.
“The northern half of the state finished summer with between 1 and 4 inches below average precipitation,” Ford wrote, “while southern Illinois was 1 to 6 inches wetter than average this last season.”
The statewide divide was pronounced in August. According to Ford, “Statewide August total precipitation was 2.01 inches, 1.58 inches below the 30-year normal and the 15th driest on record. However, like the varying temperatures, the southern and northern halves of the state experienced two very different August precipitation patterns.
“We can contrast the two halves of the state by comparing total rainfall in the Quad Cites with that in the St. Louis Metro East,” he added, with the Quad Cities Airport in Moline measuring just 0.15 inches of rain in August, less than half the previous low August record of 0.35 inches set in 1971. “As the Quad Cities experienced their driest August on record, the station at the (Southern Illinois University) Research Farm in Belleville observed their wettest at over 10 inches of total rainfall last month.”
Ford drew special attention to a storm that dumped more than 5 inches of rain on Scott Air Force Base near Belleville in just three hours on Aug. 12.
That was two days after the derecho swept across the northern half of the state, with winds exceeding 100 miles per hour. Iowa bore the brunt, with gusts measured at 140 miles an hour, although the storm damaged between 6 and 10 million acres of crops across both Iowa and northern Illinois.
Temperatures were more moderate across the state this summer than they were in Chicago. According to Ford, “June and July this year were both in the top 30 warmest months on record, resulting in an overall warmer-than-average summer in northern Illinois. However, the cooler August pushed summer temperatures within a degree of the long-term average in most of southern and south-central Illinois.”
Ford projects that “cooler weather in September will help to temper ongoing drought in northern and central Illinois. However, September is one of the drier months in Illinois, and given the outlooks, it is unlikely that dry conditions will be completely alleviated.”