Experts say pigs thrive when temperatures are between 65 and 85 degrees, and because of the multiple days in the triple digits, many are not making weight.
"When that gets out of that temperature or comfort index, whether it's low or high the the pigs won't perform very well," said Lindy Miller of the Purdue Ag Extension.
And as temperatures climb the pigs can become sluggish and not want to eat, affecting their overall weight.
Kids who show the animals rely on their weight to sell them at auction after the fair is over.
"There's a market range where where these pigs are best marketed at, and that's between 230-280 lbs so that's when you can get your best prices for the pigs," said Miller.
And the lack of rain can put even more pressure on the owners, and their livestock.
"Daily care when the temperatures are out of these animal comfort ranges can make all then difference in the world," said Miller. "If you don't take especially good care of them and that includes an awful lot of water, which some people may not have access to in this drought, then those pigs are not going to grow as fast, or where you even need them to be.
But experts say don't let one bad year spoil the whole bunch.
"One year for a kid, he shouldn't give up, I mean he should stay in it and stay with it and raise pigs the next year because by the time you get done with 10 years and selling these pigs at auction, that profit can really help in college or whatever training or education needs you might have," said Miller.
The Vigo County Fair runs now through Saturday.