Fin Shepard, [Ian Ziering], and his former wife, [April Wexler], are traveling to New York City to promote How to Survive a Sharknado and Other Unnatural Disasters, a book April has written about the Los Angeles sharknado. As the plane makes its approach through a fierce storm, the aircraft is battered by airborne sharks, losing an engine in the process. The chaos inside the cabin escalates as sharks invade the cabin, killing passengers and the crew, including both pilots. In a desperate bid to save everyone, Fin manages to guide the plane toward a rough landing, but not without tragedy: April’s hand is severed when she tries to shoot a shark with an air marshal’s handgun.
Fin’s sister, Ellen Brody, [Kari Wuhrer], is sightseeing in New York with her family. Her husband, [Martin Brody], [Mark McGrath], a childhood friend of Fin’s, takes their son, [Vaughn Brody], [Dante Palminteri], to a Mets game at Citi Field, accompanied by Martin’s and Fin’s friends Skye, [Vivica A. Fox], and Bryan, [Judah Friedlander]. Meanwhile, Ellen takes Mora Brody, [Courtney Baxter], to the Statue of Liberty, where she meets with her friends Polly and Chrissie, [Tiffany Shepis], who fill her in on Fin’s recent appearance. The city’s tension mounts as a storm of unknown scale approaches, and Fin tries to warn the crowd at the airport, but his warnings fall on deaf ears.
After handing April over to hospital care for surgery, Fin manages to contact Ellen and urges her to hurry to the Bales Tower Hotel in Manhattan. He agrees to retrieve Martin and Vaughn from the ball game and enlists a cab driver, Ben, to help. At Citi Field, Skye surprises Fin with a kiss, but he makes it clear that he and April are back together. The game is canceled as the storm intensifies, and sharks begin falling from the sky, slaughtering people and creating a melee of improvised defense. Fin and his group improvise weapons from the surrounding stores and move toward the subway for safety.
On the ferry back to Manhattan, Chrissie is killed by a shark, and the trio of Ellen, Mora, and Polly flee the fearsome spectacle near the severed head of the Statue of Liberty. In parallel, the subway tunnels flood, and sharks breach the train’s rear cabin, killing Brian. Ben, who anticipated Fin’s escape, steers Fin and the others to a sequence of shops to gather materials for improvised explosives. When the taxi scene goes awry and floods close in, Fin constructs a rope swing to transport Skye, Vaughn, and Martin to safety. The rope ultimately gives way after Ben is killed, and Fin must improvise by using the toppled sharks as stepping stones to reach the others.
Two sharknadoes converge into a single, more powerful storm directly above the hotel. Fin and Skye rush to the roof to set off bombs aimed at dismantling the tornadoes. Polly is crushed by a whale shark, but Ellen and Mora reach the hotel and are reunited with Martin and Vaughn. Fin and Skye continue to drop bombs into the tornadoes, yet the cold air makes the effect limited; only a handful of sharks fall, forcing the survivors to flee down a fire exit stairwell as the building fills with water and danger.
The group makes contact with the Brodys above, and they break through a door to escape the increasingly flooded stairwell. April flees the hospital and commandeers a fire truck to reach Fin and the others. At the Empire State Building, a third tornado looms, threatening to merge with the others. Fin devises a bold plan: detonate a tank of Freon at the top of the building by wiring it to the structure’s lightning rod to halt the storm. He rallies a crowd of New Yorkers, including the mayor, [Robert Klein], and his task force, to help withstand the onslaught of sharks.
As the plan unfolds, April—who has ingeniously attached a circular saw to her stump for protection—arrives and saves Fin from a collapsing shark. Skye sacrifices herself to help connect the power cables; the Freon detonation sends everyone hurling through the air, and a great white shark tears Skye in half. Amid the chaos of the twister, Fin clings to a shark using chains, riding it upward and then driving it into the building’s antenna. He is eventually able to reunite with April and even recovers her lost arm from a fallen shark, using a handgun to finish off another threat. In a final, tender beat, Fin retrieves the wedding ring from April’s severed hand and uses it to propose remarriage, which April accepts, offering a quiet, hopeful close amid the devastation.
