Plot

A deadly category 7 storm wreaks havoc on the world. Meanwhile, kidnappers threaten to make matters even worse.

It's tornadoes, hurricanes, electrical storms, and mass destruction as the effects of global warming brew into a super storm that threatens to rend the earth with an unprecedented power. Beautiful scientist Faith Clavell, storm chaser Tommy Tornado, and Judith Carr, the head of FEMA, can stop the inevitable from happening-if they have the courage to venture into the roiling blackness of the storm itself.—Echo Bridge Home Entertainment

Following the events in Category 6: Day of Destruction, the superstorm that hit Chicago is continuing to grow in size and strength, with tornadoes hitting Paris and destroying the Eiffel Tower. Judith Carr (Gina Gershon), the new head of FEMA struggles to coordinate efforts to prepare for the aftermath of the storm and provide aid to ravaged areas. She calls in her former college lover, Dr. Ross Duffy (Cameron Daddo), and her father Senator Ryan Carr (Robert Wagner) to help her try to determine what is causing the storms and how to deal with the political issues. Tommy Tornado (Randy Quaid), who survived his seeming death in the previous film, returns to aid in tracking the storm in the United States, assisted by scientist Faith Clavell (Shannen Doherty). Similar storms are developing around the country and an interaction between urban heat islands and "falling chunks of mesosphere" fuels the storms making them more powerful. Hurricane Eduardo strikes toward Florida while the Category 6 storm hits Buffalo and heads towards New York City.

During these catastrophic events, two Christian fundamentalists (James Brolin and Swoosie Kurtz) fake the arrival of the plagues of Egypt to lure in new converts, culminating in their kidnapping of the first-born children of Judith Carr and other high-ranking officials. When Tommy and Faith get their data to FEMA when in New York, Judith realizes that Hurricane Eduardo is heading towards Washington, D.C. and the Category 6 storm in New York is heading in the same direction. When both storms collide with the mesosphere, it turns into a "Category 7" hurricane, obliterating anything in its path. The force of the storm is so massive, that a category 7 could potentially cause a global catastrophe, possibly leading to the apocalypse (hence the title).