why is indiana so humid

Why is Indiana so humid? No doubt, Indiana is known for its humid climate, and it truly gets hot in the summer months.

Those who want to move to this state often feel confused about its climate. So, does Indiana have high humidity as well?

And if it does, what factors contribute to its muggy conditions?

All these questions make Indiana an intriguing state for locals as well as climate enthusiasts.

And what makes it even more interesting is the fact that this humid weather is due to many complex factors.

Indiana is so humid because of its geographical location, topography, and various meteorological factors. 

Why Is Indiana So Humid?

reasons for humidity in indiana

Located in the Midwestern region of the country, Indiana is famous for its diverse landscapes.

However, it is also rather infamous for its fluctuating weather conditions. In fact, the first thing you will notice in Indiana is how humid the climate is.

Indiana’s summers can be unpleasant, if not downright miserable, due to the state’s high average annual humidity.

And the high humidity is due to various factors, including:

  • Geographical Location
  • Topography
  • Meteorological Factors 

Geographical Location

geographical location

The location of Indiana is a major factor in the state’s consistently high humidity.

Due to its location in the middle of the country, Indiana has a humid continental climate with hot summers and frigid winters.

The state’s proximity to the Great Lakes and the Ohio River also contributes to the high humidity there.

Here is a bit more about how the Great Lakes and the Ohio River have a role to play in making Indiana as humid as it is today:

Great Lakes

great lakes

The Great Lakes is an enormous system of interconnected freshwater lakes encompassing Michigan, Huron, Superior, Erie, and Ontario.

It has a significant impact on the local climate in Indiana.

Indiana’s climate is directly influenced by the massive Lake Michigan, which shares a border with the state’s northwest.

Fact: The Great Lakes contain nearly 84% of the freshwater on the surface of North America, making them a reliable source of moisture year-round. 
How the Great Lakes Affect Indiana?

Interestingly, they cover over 94,000 square miles, and definitely have a role to play in climate.

The evaporation process speeds up when temperatures rise throughout the summer, releasing a lot of water vapor into the air.

Winds from the west and southwest, in particular, bring this damp air to Indiana, greatly raising the state’s average humidity.

This surge of humid air can cause unbearable heat and even promote the growth of convective storms, which add to the already oppressive humidity of an Indiana summer. 

Ohio River

ohio river

When it comes to weather, Indiana is like the other states along the 981-mile-long Ohio River.

The Ohio River, which forms Indiana’s southern border, has a significant impact on the state’s relative humidity.

The Ohio River begins at the point where the Allegheny and Monongahela Rivers meet in Pennsylvania.

It then flows through several states before it reaches the Mississippi River at its confluence with Illinois.

The river provides a significant amount of moisture to the environment along its course by evaporating large quantities of water into the atmosphere. 

The Effect of the Ohio River on Indiana
effect of the ohio river on indiana

Particularly during the hot summer months, fast evaporation contributes to Indiana’s already high humidity levels.

More rain, and heavier rain, can fall because the river influences localized weather patterns, especially during the summer’s thunderstorm season.

In general, the Ohio River’s role as a moisture supply raises the relative humidity in Indiana, making the state’s climate humid and less pleasant during the summer. 


The geography of Indiana also plays a role in the state’s consistently high humidity.

The southern half of the Hoosier State, in particular, has more diversified terrain than the rest of the state. 

Low-Lying Areas

The middle and northern parts of Indiana, in particular, are characterized by low-lying landscapes.

Humidity tends to be higher in these low-lying regions because of the ease with which water can accumulate there.

low-lying areas

Stagnant air masses, which can form due to the flat landscape, can trap moisture and increase humidity. 

Southern Indiana Hills

In contrast, Brown County and the surrounding area in southern Indiana are characterized by rolling hills and woodlands.

This varying topography can also contribute to the state’s humid conditions by fostering the development of microclimates that are more humid than their immediate surroundings.

Fact: The hills and forests may act as natural barriers, slowing the evaporation of moisture and resulting in increased humidity levels in certain areas. 

Meteorological Factors

meteorological factors

When talking about humidity, it is important to consider various meteorological factors.

Several weather elements, as well as Indiana’s location and topography, contribute to the state’s high humidity. 

The High-Pressure Systems in Summer

High pressure systems typically dominate the weather patterns over the United States and the Midwest during the summer months.

And the same holds for Indiana.

Humidity levels in Indiana may rise as a result of these high-pressure systems, which can contribute to the formation of stagnant air masses.

The absence of airflow causes humidity to rise, making the environment rather unpleasant. 

Gulf of Mexico Influence

gulf of mexico influence

The influence of the Gulf of Mexico on Indiana’s climate is another contributor to the state’s high humidity.

In the summer, Indiana can receive warm, humid air from the Gulf of Mexico thanks to the prevailing southerly winds.

Humidity levels in the state may rise dramatically due to this influx of wet air, which is especially noticeable during the summer. 

Precipitation Patterns

precipitation patterns

Humidity in Indiana is influenced by both local and regional precipitation patterns.

Precipitation in Indiana is above average yearly, with the majority of precipitation falling during the summer.

Saturation of the ground from heavy rain and thunderstorms can raise air moisture content.

Humidity rises as a result of the added moisture in the air, creating an unpleasant and stifling environment.

Fact: Annual precipitation varies significantly across the state, but Indiana witnesses anywhere between 47 inches and 37 inches of rain every year. 

Additional Factors Contributing to High Humidity in Indiana

contributing factors in high humidity in indiana

In addition to some major contributing factors, there are some others at play making Indiana truly humid.

For instance: 

Urban Heat Island Effect

Cities in Indiana, such as Indianapolis, raise the state’s average temperature and humidity through a process known as the urban heat island effect.

Heat-absorbing surfaces like buildings and pavement, combined with a lack of flora, cause cities to be substantially warmer than their rural counterparts.

Humidity levels in cities may rise as a result, because hotter air holds more water. 

Climate Change

climate change

Humidity may be rising in Indiana because of climate change and other factors.

The ability of the atmosphere to retain moisture rises as global temperatures continue to rise as a result of human activity.

Particularly in the summer when the air is already warm and moist, this might lead to increased humidity levels.

It’s possible that changes in Indiana’s precipitation patterns due to climate change will bring about heavier rains more frequently. 

Is Indiana the Most Humid State in the United States?

Not Really!

Alaska has the highest average humidity of any state in the USA.

Although it comes as a surprise that Alaska is the state with the highest RH, there is a good rationale for this fact.

humidity ranking of indiana in usa

Humidity is often around 77% in Alaska. The next most humid state is Florida, with an average RH of about 74%.

Florida has a warm and humid summer, but Alaska, with its cold winters and cool summers, wins hands down.

Despite there being significantly less moisture in the air, the relative humidity (RH) can be substantially greater in colder places.

The reason being, cold air has a considerably lower capacity for holding moisture than warm air.

Nonetheless, Indiana is definitely not the most humid state, but it is certainly among the top-10 most humid states in the U.S. 

An Important Consideration

While this may seem like a trick question, it serves to highlight some of Relative Humidity’s shortcomings.

It does not always accurately predict how humid it will feel outside or how much moisture is actually in the air.

Fact: Pleasant Lake and Auburn are two cities in Indiana experiencing the highest average humidity throughout the year. 


Why is Indiana so Humid?

There is actually more than one reason why humidity levels in Indiana are high and keep crawling up by the day.

geography and topography

Its geography and topography have a role to play, but several metrological factors are also at play.

While Indiana is certainly not the most humid state, it is surely among the top names.

And it is moving up the list, especially due to climate change and global warming effects.