The town of Swallow Falls, located on a small island located under the “A” in Atlantic Ocean on the world map, is left with the remaining sardines as the only food source, weakening the economy, is going to close for good.

Flint Lockwood (Bill Hader) has always wanted to invent something awesome, though everything he invented - including Spray-On Shoes, the Remote Control Television, Hair-unbalder, Flying Car, and Ratbirds - has ended in nothing but disaster. To help solve the food problem, Flint invents a machine that converges water molecules to create food.

When finally one day, his unsupportive and technophobic father Tim Lockwood (James Caan) can’t stand Flint anymore, he forced Flint to work at his Bait N’ Tackle shop.

On the day of opening of the Sardine Tourism, Flint along with his pet monkey Steve (Neil Patrick Harris), fuses the power station's electricity to work the machine. Unfortunately, the machine has absorbed so much power that it explodes like a rocket, destroys Sardine Land, and travels up into the Stratosphere. Flint escapes an angry mob, and hides under the docks sulking at his failure. Then he meets Sam Sparks (Anna Faris), a cute weather intern whose big break was ruined by Flint’s “rocket”.

The two witness giant purple clouds raining cheeseburgers over Swallow Falls, Sam reports the events and mentions Flint is responsible. Everyone begs Flint to make it rain more. After Flint explains the work of the FLDSMDFR (Flint Lockwood Diatonic Super Mutating Dynamic Food Replicator) and builds a communication device, he starts taking requests from citizens. Sam allows free advertising, and Mayor Shelbourne (Bruce Campbell), the greedy mayor, gets the money to rebuild society in Swallow Falls, even allowing the name to be changed to Chewandswallow.

Moving on to the end when Flint and the others got no choice but to fly into the stratosphere to find that the FLDSMDFR is shelled in a giant meatball where water clouds enter from the top and a food hurricane exits from the bottom.

In the end when Flint came back safely, Tim finally admitting that he is proud of his son, explains his thoughts through Steve’s thought translator, and Sam and Flint share their first kiss. During the credits sequence, Chewandswallow is renamed Chewandswallow 2, Flint and Tim open a business that uses the Spray-On Shoes formula to fix rooftops, and the Mayor is arrested by Earl and Cal.