Flint Lockwood is a wannabe-scientist who lives in Swallow Falls, a tiny island in the middle of the Atlantic Ocean that has sardines as the base of its economy. Flint lives with Tim, his widowed technophobic father who misunderstands his son’s talent, and his pet monkey, Steve. Despite Flint’s zealous enthusiasm, his inventions, including spray-on shoes, a remote controlled television, rat birds, hair-un-balder, and a flying car, all ended in failure. Flint states that his dream was to help his hometown and that Swallow Falls used to be famous for sardines until the popular Baby Brent Sardine cannery went out of business permanently.
Flint then invents a machine that transforms water into food, called the “Flint Lockwood Diatonic Super Mutating Dynamic Food Replicator” (FLDSMDFR). Flint turns on the FLDSMDFR in his laboratory, but ends up overloading the house’s electrical supply. He then decides to power the machine by hooking it up to a nearby power plant. When he turns the machine back on, it ends up rocketing through town, causing widespread damage, ultimately shooting up into the sky. While recovering from his failure, Flint meets Samantha “Sam” Sparks, a weather intern whose big break was foiled by Flint’s actions. Their conversation is cut short when rainbow colored clouds float over the town and begin to rain cheeseburgers.
The town rejoices in their renewed food choices, and Flint creates a communication device to send orders to the machine and order it to create different types of food. Swallow Falls (now renamed Chewandswallow) suddenly becomes a successful “food tourism” destination. Everything is going well until the townsfolk start greedily requesting food from Flint’s machine. Flint notices that the food is beginning to grow larger in size. Although he is concerned that the food is starting to “over mutate”, the now morbidly obese mayor sees it as profitable for him and the city, and guilts Flint into continuing to make food rain.
Citizens and worldly tourists in Chewandswallow are blissful until suddenly a large tornado formed of spaghetti and meatballs threatens the town. Flint rushes to his lab to turn the FLDSMDFR off and attempts to send a “kill code” to stop the machine, but the mayor, while trying to stop him by throwing a giant radish at him, accidentally destroys the communication device before he can do it. With Flint unable to control the machine, a massive food storm is created which threatens the world. When Flint’s father encourages him to fix the mess, Flint gains self-confidence, places the kill code in a USB flash drive, and builds a new flying car to reach and deactivate the FLDSMDFR, with the aid of Sam, her cameraman Manny, Steve and Brent (namesake of the Baby Brent Sardine cannery).