Is it true that July is one of the wettest months of the year in Indiana? If so, why? Many people think of July as hot and dry. Let’s see if we can separate fact from fiction.

Everyone knows the phrase “April showers bring May flowers,” but April isn’t even the wettest month of the year in Indiana. That honor falls to May. In Indianapolis, the 30-year average monthly precipitation for May is 5.05 inches. That’s a half inch more than July, the second-wettest month with an average of 4.55 inches. June rounds out the top three with 4.25 inches of precipitation.

Pretty much everywhere across the state, May is the wettest month, followed by some combination of June, July, August and occasionally, April. Clearly here in the Midwest, spring and summer are the wettest months, but May usually takes the cake.

These spring and summer months are usually the wettest due to a combination of factors, including warmer temperatures and a shifting of the jet stream. As the jet stream moves farther north in the spring, warmer, more moist air returns and allows for more convection and development of rain and thunderstorms. In contrast, frontal systems dominate the colder seasons and create the winter storms that were so prevalent last winter.

Hot, not dry
The concept of July and August as hot and dry months is only half true. July and August are the two hottest months of the year, but not the driest. Most Midwesterners know that summer can be downright muggy at times in July and August, with tropical humidity accompanying the high temperatures. On the contrary, the driest months are winter months — in most cases, January or February.

So July is one of the wettest months in most areas of the state, and while hot, could never be described as dry — unless a drought hits like in 2012.

Eggert works in the Indiana State Climate Office.