Despite the warmer temperatures Wednesday, State Climatologist Harry Hillaker says August could break up a 10-month long streak in Iowa. Temperatures in August have averaged roughly two-and-a-half degrees cooler than normal.
“Chances are fairly good we’ll end the month with below average temperatures, despite warmer weather off and on the next week or two,” Hillaker said. The cooler-than-normal trend in August is a drastic change from July – which entered the record books as the fourth warmest month, on average, in Iowa history.
“We haven’t had a month averaging below normal dating all the way back to September 2011 and many of those months were quite a bit above normal” Hillaker said. “This has been quite a change from what we’ve been seeing.” In July, the capital city of Des Moines recorded 10 days with a high temperature of at least 100 degrees. In August, there have been five days where multiple cities have posted record low temperatures.
“Part of that is related to the fact that it’s just so darn dry,” Hillaker said. “We have very low humidity, which allows air to cool off much more at night than it would otherwise and that makes it easier to get unusually low temperatures.” Iowa has posted nine consecutive weeks with below normal precipitation.
There have been some unusual single day temperature swings in August as well. For example, on Tuesday, Hillaker said Mason City hit a low of 41 in the morning before warming up to 81 in the afternoon.