A series of tornadoes, culminating in a massive EF-5 tornado, destroys the town of Silverton, Oklahoma. Several townspeople are killed, as are stormchaser Jacob and filmmaker Pete. Everyone else survives, including Donk and Reevis.
In the town of Silverton, Oklahoma, the local high school is preparing for it's graduation ceremony. Vice-Principal Gary Fuller has asked his two teenage sons, Donnie and Trey, to videotape the outdoor ceremony as well as make a time-capsule video of the graduates to be played back at their 25th reunion. Donnie decides instead to go to an abandoned paper mill to help fellow student Kaitlyn complete her own project. Meanwhile, documentary filmmaker Pete Moore and a team of stormchasers are near Silverton preparing to film an impending storm, hoping to catch a tornado. He plans on driving his chase vehicle, dubbed Titus, into a tornado in order to film inside it. When they drive through town, they are spotted by Donk and his brother Reevis, a pair of locals who are always filming themselves doing dangerous stunts, hoping to get famous on YouTube. They decide to follow the Titus and shoot the storm on their cellphones. The storm does form a tornado, and Pete is about to get that shot inside it when it abruptly turns away and heads directly towards the high school. When the storm sirens go off, Gary and the rest of the faculty safely get the graduates and their families inside and to the school's storm shelter just as the tornado hits, damaging the school. The same tornado also hits the paper mill, trapping Donnie and Kaitlyn in a hole underneath the rubble.
Gary is able to call Donnie and learn where he is before Donnie's phone dies. Just then, a water pipe bursts, flooding the hole where they are trapped. Gary and Trey then leave the school and drive through town to get to the paper mill, and meet up with the stormchasers, where he asks them for help. They agree, and as they are all driving to the paper mill, another storm system forms over Silverton, creating several tornadoes. These tornadoes cause heavy damage to the town, and also trap the team near a gas station, with one of the tornadoes causing a fire, turning it into a "fire-nado". Donk and Reevis, who were still following the stormchasers, try to film themselves with the tornadoes behind them, but they get too close and are sucked in by one of the tornadoes. Jacob, one of the stormchasers, tries to film the "fire-nado", but he also gets too close and is sucked in. Because this tornado was on fire, he is seen burning up as he is blown away. His death angers the remaining stormchasers, as they feel Pete is only interested in the footage of the storm rather than the team's safety. Despite this, the team continues to the paper mill. They arrive and use the Titus to rescue Donnie and Kaitlyn just before they drown.
While everyone is seeing to Donnie and Kaitlyn's injuries, Allison, the lead stormchaser, sees that yet another storm is approaching Silverton, and this one is going to produce a massive EF-5 tornado, which can produce winds over 300 mph. This tornado is heading straight for the high school, and the surviving townspeople have gathered there to hide in their storm shelter. Since the previous tornadoes damaged the town's storm sirens and the phone system is down, nobody there will know that another tornado is approaching until it's too late. The team leave the paper mill and head back to the school, where Gary and Allison convince everyone that the shelter isn't safe, and they are directed to get on school buses and drive out of town. Everyone makes it out just before the EF-5 hits the school, destroying it. Gary and his boys are on the last bus in a line out of town, followed by Pete and the stormchasers, when a transmission tower falls in front of them, blocking their path. They turn around to get out of town another way, but that way is blocked by the tornado. Out of options, the group drives to a construction site, where a new storm drain was being built, and everyone hides inside it.
A grate at one end of the drain is damaged, compromising the integrity of their shelter, so Pete leaves to place the Titus in front of the grate. He uses the Titus' winch and ground anchors to lock the vehicle in place, but the Titus is not designed to handle winds over 170 mph. When the tornado reaches them, everyone is safe. As the eye of the storm passes over the Titus, Pete finally gets the shot he's been waiting for. But when the back half of the tornado hits, it becomes too much for the Titus and it's picked up, with Pete still inside, and carries him up several hundred feet. He is so high that he is above the clouds and can see the sun, but soon he is slammed back down to earth, killing him instantly. The storm soon dissipates, and everyone leaves the drain. They go back to town and see it's been completely destroyed.
The movie ends with the surviving townspeople rebuilding Silverton. Trey finished the time-capsule video, and it features students who are just happy to have survived and have a new-found respect for life. The last scene shows that Donk and Reevis survived the storm and are stuck in a tree. The got their video and will get their fame on YouTube.