The first day of fall, when the Autumnal Equinox occurs, is September 22 at 9:04 p.m. With the fall season, temperatures get lower, days get shorter and the leaves change color. 

What is Autumnal Equinox? 

Equinox is the Latin word for equal nights, meaning we will have 12 hours of sunlight and 12 hours of daylight on Thursday, September 22. On this day, the sun’s rays are directly over the equator. 

The equinox officially occurs at 9:04 p.m. 

When do fall colors peak in Indiana? 

For various parts of the state, fall colors peak at various times. For the northern part of Indiana, peak fall foliage is usually the beginning of October. For Indianapolis, it is usually mid to late October. For southern Indiana, peak fall foliage is at the end of October. 

Why do leaves change color?

What is the science behind why leaves change colors?

With cooler weather during the season, the chlorophyll breaks down, leaving behind other chemicals that cause color changes in the leaves. For example, if the leaf is yellow, xanthophyll has been left behind. 

The summer season impacts fall colors. Bright colors are more likely when late summer is dry and fall has sunny days and cool nights.  

In order to reach peak fall foliage, we need a few ingredients.  

  • Chilly nights 
  • Mild, sunny days 
  • No big storms 
  • First light frost 

Typically, our first light frost varies from the end of September to the end of October, depending on which part of the state you are in. 

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