'Flash Drought' Hits Illinois

By Chuck Sudo in News on Sep 13, 2013 4:30PM

Photo credit: Phil Trusky

Illinois was cruising along with a mild summer before August brought a slew of hot and muggy 90-degree days. That humid weather didn’t result in any real rainfall and September has been more of the same. Now the state is in the midst of what climatologists is calling a “flash drought” with Cook County having been declared “exceptionally dry”

The average statewide precipitation for August, according to State Climatologist Jim Angel, was 1.38 inches. That was the third driest August on record, 2.22 inches below the average rainfall from 1981-2010 and 2.26 inches lower than August 2012’s total, when it was recognized we were in a drought.

The average statewide precipitation for June, July and August was 9.93 inches, 1.92 inches below average. Most of that rain came in June and early July, which helped Illinois corn crops rebound from last year’s paltry yield.

Pollination conditions were good in most places, with adequate soil moisture and generally good temperatures. By late July most fields were in good shape, with good kernel counts and good canopy color and leaf health.

Much of the crop reached the middle part of August in good shape, helped along by continued cool temperatures. But rainfall became infrequent or stopped at some point in July or August, depending on location. At Champaign, July rainfall was slightly above average, with 5.03 inches at the airport, more than half of which fell on July 21. Many areas received much less than this.

Temperatures continued to be part of the weather story, with growing degree day accumulations well below normal during the last week of July (with barely more than 100 GDD at Champaign) and again the third week of August. That changed to above-normal temperatures the last week of August, and since then, weekly GDD accumulations have been above normal, with the total for the first 10 days of September 234 GDD, nearly half the normal total for the month.

Despite the hot, dry weather of recent weeks, corn in many fields has retained some green color, at least in the upper canopy, and it appears that kernels continue to fill. That may not be the case in some of the drier parts of the state, where the crop either ran out of water earlier in August or where canopy color wasn’t very good even before that.

The average rainfall in Illinois year-to-date is at 33.48 inches, nearly double last year’s 17.79 inches through the end of August.