The third day of Governors Ball 2016 was unfortunately cancelled, and the GovBall team has now posted more info about their decision. They write:

We work 362 days out of the year for three special days each June. We are devastated that we were unable to have Day 3 but a decision was made with the Mayor's Office and Parks Department based on forecasted severe weather, for your safety. The festival site was indeed hit with a quick, yet extremely strong storm. The result was flooding, 40+ MPH winds, damaged fence & trees, nearby lightning, and truly unsafe conditions. For more information or to talk with us about the decision (and the decision making process), please join our REDDIT AMA tomorrow @ 1:00 PM EST.

Miss you already, love you forever.
- Tom, Jordan, and the rest of Team Gov Ball

They also posted pics of the wreckage caused by that storm, which you can see in this post.

More pictures of Governors Ball days 1 and 2 here, here, and here.