But it wasn't all fun for everyone.
"I actually had a friend not too long ago, we were in the middle of the crowd and she did pass out," Victoria Villarreal told us. "She blacked out right in front of me. It was probably one of the scariest moments in my life."
Medical volunteers told us dozens of people needed medical attention throughout the day -- some more than others.
About 10 people had to taken out of the festival and to a hospital.
"Mostly, we've seen a lot of exhaustion, minor to moderate dehydration," Richard Williamson with Alliance Ambulance said.
Medical workers said this is why they have tents set up throughout the park, ready to help anyone who needs it.
"Dehydration, couple of people have had fainting spells, but that's all related to dehydration and heat exhaustion," medical volunteer Heather James-Davis said.
James-Davis told us they treated some people for minor scrapes, bruises and sprains, but dehydration is always their main concern.
Many we talked to said they came out knowing its hot and they need to play it smart.
"I drank a million bottles of water before I came here," Katie Hamarich said. "You have to drink a lot of water."
"Some people aren't prepared for it and will come and not know what to expect," Emory Gonzales said. "But you're out in the sun all day. It's Houston."
Free Press Summer Fest continues through Sunday evening. Medical volunteers suggest you bring your own water and be smart when it comes to having fun in the sun.