Weather in Indianapolis: Climate, Seasons, and Average Monthly Temperature

Indianapolis skyline with a fountain and park during Autumn
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There's a popular phrase that goes around in Indiana: "If you don't like the weather, stick around, it will change." That's not to mention the shared belief that Indy experiences all four seasons in a single day.

The weather in Indianapolis is unpredictable and changes rapidly. On your way to work you could be blasting the heat in your car, and on the way home, you've got the air conditioning cranked up.

Still, there are certain times of year that are more mild and pleasant than others. May, June, September, and the beginning of October are optimal for visiting, while January through March are less than ideal. For a season-by-season breakdown, here's your guide to the weather in Indianapolis, Indiana.

Fast Climate Facts

  • Hottest Month: July, 85 degrees F
  • Coldest Month: January, 36 degrees F
  • Wettest Month: May, 5.1 inches
  • Snowiest Month: January, 8.6 inches

Tornado Season

Indiana is no stranger to tornadoes, but recent years have seen a significant increase in the number of storms—so much so that researchers have placed the state in "Dixie Alley," which is an eastward extension of "Tornado Alley."

In Indianapolis (and central Indiana in general), peak tornado season starts in the spring and runs into early summer. Fall sees a second batch of tornadoes, but they are not as common.

If you're worried about tornadoes during your visit, you can rest easy. Marion County has only reported 45 tornadoes in the last 68 years, none of which resulted in any fatalities. The last tornado to hit Indianapolis was in Sept. 2012.

Still nervous? The CDC has three tips for staying safe during a tornado.

Spring in Indianapolis

In Indiana, March comes in like a lion... and goes out like that same lion. Spring in Indianapolis is unpredictable and difficult to prepare for. One day, it's 65 degrees F, and the next it's 15. It's windy, it's freezing, it snows—it's one of the worst times of year to visit Circle City. Unless you don't mind the cold and slush—or plan to spend most of your time hitting up museums—you should try to book your trip to Indy later in the spring.

It can—and has—snowed in April and May before, and May is the wettest month of the year. When the weather is nice, though (we're talking 72 degrees F and sunny), it is rather lovely. Try to come during late spring, towards the end of May. Walk the canals, take a stroll down the Monon trail, or feed the giraffes at the Indianapolis Zoo—it's so nice you'll never want to head inside.

What to pack: Layers, layers, layers. If you're coming in March or April, you need to be prepared for all types of weather. Pack cardigans, sweaters, jeans, a heavy winter coat, gloves, hats, snow boots—but save room for a light jacket, T-shirt, a pair of shorts, and a dress or two. Feel free to leave the winter clothes at home if you booked your trip for the end of spring.

Average Temperatures by Month:

  • March: High: 52 degrees F; Low: 33 degrees F
  • April: High: 63 degrees F; Low: 43 degrees F
  • May: High: 73 degrees F; Low: 53 degrees F

Summer in Indianapolis

If you had to pick any time of year to visit Indianapolis, early June would be a safe bet. It's warm—but not too hot—and the humidity hasn't yet come out in full force. It looks and feels like everything you wish spring could be. Later in the month, you'll begin to see thunderstorms, which continue on through July.

Temperatures escalate in July and August (it can get over 100 degrees F in the city), and the humidity can be a beast to bear. However, summer in Indy comes alive with activity: there are concerts, the Indiana State Fair, farmer's markets, and more. August sees the least amount of rain out of all the summer months; book a trip at this time if you have a lot of outdoorsy activities in store and aren't afraid of a little humidity.

What to pack: Summer is hot and humid, so you're going to want to pack your lightest (and most sweat-proof) clothing: shorts, T-shirts, sundresses, sandals, sneakers, tank tops, and breezy blouses. Since a summer night in Indy is just as humid as a summer's day, you do not necessarily need to carry a light jacket or cardigan for evening activities. However, you may want to bring one just in case you get cold in air-conditioned buildings. Don't forget your umbrella!

Average Temperatures by Month:

  • June: High: 82 degrees F; Low: 62 degrees F
  • July: High: 85 degrees F; Low: 66 degrees F
  • August: High: 84 degrees F; Low: 64 degrees F

Fall in Indianapolis

For most Hoosiers, fall is the best time of year: the humidity has died down, it's crisp, it's comfortable, and football season has started. September and October are some of the more mild months in Indy, although it can get below freezing some nights in October. November is when the chill starts to hit and you can feel the beginnings of winter.

What to pack: You should pack lots of layers in the fall. You can get away with shorts and dresses at the beginning of September, but you should have a jacket on hand just in case you get cold at night. Be sure to pack jeans, sweaters, scarves, sweatshirts, a light jacket, and a pair of boots.

Average Temperatures by Month:

  • September: High: 78 degrees F; Low: 56 degrees F
  • October: High: 65 degrees F; Low: 45 degrees F
  • November: High: 52 degrees F; Low: 35 degrees F

Winter in Indianapolis

Even though the average high in January is 36 degrees F, it's not uncommon for Indiana to experience temperatures in the negatives. December experiences the most mild winter, whereas January and February are the two coldest months of the year. If you only plan on checking out the museums and hitting up the city's breweries, this is the time to go. Otherwise, you should plan your trip for another season.

What to pack: Pack all your warmest clothing (that includes a pair of long Johns). You should bring your warmest sweaters, thermals, scarves, gloves, hats, coats, pairs of pants, and snow boots. While our neighbors to the north might not think anything of an Indiana winter, it's always best to be prepared.

Average Temperatures by Month:

  • December: High: 39 degrees F; Low: 24 degrees F
  • January: High: 36 degrees F; Low: 21 degrees F
  • February: High: 40 degrees F; Low: 24 degrees F
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