Extreme heat compounding problems caused by drought
July 6th, 2012 by Ric Hanson
Much of Iowa is in the midst of the state’s worst drought in 24 years. State Climatologist Harry Hillaker says Iowa’s rainfall totals over the last two months were less than half of normal amounts for May and June. “Probably the worst off area over that relatively short term would be in east-central and parts of northeastern Iowa,” Hillaker says. “Around Waterloo, Cedar Rapids, Quad Cities and Dubuque…those areas, in many cases, have maybe received 25-percent of normal rainfall over the past couple of months.”
In addition to the lack of rain, temperatures have been well above normal this spring and summer. The situation is similar to 1988 – the year of Iowa’s last major drought. “1988 is certainly the year that we’ve probably been comparing 2012 with the most often,” Hillaker says. “That particular summer was both unusually hot and unusually dry.” But, Iowa’s received nearly twice as much rain over the first half of this year compared to 1988. A report from the USDA this week found 73 percent of Iowa’s farm acres were either “short or very short” on subsoil moisture — that compares to just two-percent at this time last year. Hillaker says the recent heat wave is stressing crops even more.
“When temperatures are at 100 degrees or so, it basically results in evaporation rates roughly 25 to 30 percent higher than what would be the case if we had more normal temperatures, which at this time of year would be in the mid 80s,” Hillaker said. “It does make quite a bit of difference and dries things out much more rapidly than if we had moderate temperatures.” Monday’s USDA report rated 62-percent of Iowa’s corn as “good to excellent.” That compares to an 82-percent rating in Iowa at this time last year. Scattered showers and storms are in the weekend forecast and more normal temperatures, with highs in the 80s and overnight lows in the 60s, are expected Sunday and Monday.