Preliminary findings from the National Weather Service indicates parts of Iowa saw the coldest July on record this year. State Climatologist Harry Hillaker says an unusual jet stream is one reason for the cooler weather. Hillaker says this has been good news for corn and soybean crops. He says the best yields come during cooler weather. The lowest July average temperature in Iowa was in 1891 at 68.3 degrees. This July the average has been 68.1 degrees. But Hillaker says more temperature reports could alter that number.