Megastorm may refer to:
Hypothetical storms ARkStorm, a proposed 1-in-1,000 year atmospheric river event that could impact California with historic, extremely damaging flooding Hypercane, hypothetical extreme tropical cyclones that could reach the size of continents and last for several weeks on average. Hypercanes also would have maximum sustained winds reaching at least , and a minimum central pressure of or lower.
Other uses Megastorm, a Predacon/Destron in the Transformers fictional universe
See also Superstorm, a large, unusually-occurring, destructive storm without another distinct meteorological classification