Indiana has above average chances to exceed the normal precipitation amounts for June, July, and August according to the Climate Prediction Center (CPC) summer outlook predictions. As Indiana’s climate changes to one with greater chances for drought conditions in the summer and fall seasons, this prediction provides a little relief for people with rainfed plants.
The CPC is currently predicting the statewide summer precipitation totals to be over one inch of normal amounts for southern Indiana, tapering off to within half an inch of normal for northeastern Indiana. June has equal chances of above or below normal precipitation, so the CPC expects increased rainfall to occur in the later portion of the summer. Around that time, Indiana is expected to begin experiencing the next El Nino, with El Nino Southern Oscillation (ENSO) neutral conditions currently. El Nino conditions do not have a large impact on our summer weather, with most of its impact heating the southeastern United States.
The total average precipitation (based upon data from 1991-2020) for summer months in Indiana is 12.69 inches, so an inch more precipitation may not seem too significant. However, the trend in Indiana towards increasing rainfall intensity (i.e., isolated heavy rainfall events) means that the odds that additional precipitation causes a flooding event is greater than it has been in the past.
Unfortunately, CPC precipitation outlooks have not been particularly reliable over the last several months. According to Beth Hall, Indiana State Climatologist, these outlook discrepancies may be due to climate patterns such as ENSO having too much weight within the various climate models.
“While ENSO can be mathematically associated with certain climate patterns in the Midwest, when coupled with the rapidly evolving climate change patterns the reliability of ENSO influences becomes more uncertain,” Hall said.
According to the Köppen-Geiger Climate Classification, Indiana has humid and hotter summers, relative to other climates around the world. This summer is predicted to follow the pattern of humid and hot. However, the CPC predicts an equal chance for above or below average temperatures this summer, so variability is likely to occur throughout the season. The Indianapolis airport average maximum temperature for July is 85 degrees Fahrenheit. According to climatology over the last thirty years, all three summer months average above 80 degrees at that site, with average minimum temperatures in the mid-60s. Minimum temperatures are close to maximum temperatures (i.e., the daily temperature range is small) when humidity is high.
For more information, please contact the Indiana State Climate Office at 765-494-8060 or hschmitz@purdue.edu.