I went on a date with a meteorologist.

This joke rides on the delightful waves of wordplay, specifically using puns that hinge on meteorological terms. The humor comes from taking common idioms used to describe relationships and applying them literally to a person whose job revolves around weather. A "whirlwind romance" is a popular phrase for a fast, intense, and often brief love affair, but it's also a literal weather phenomenon that a meteorologist would be intimately familiar with.

The punchline continues this clever double entendre. When a relationship gets "stormy," it means things are difficult, filled with arguments, and generally unpleasant – much like a literal storm. The brilliance is in how the meteorologist's profession provides a perfect, albeit coincidental, backdrop for these common romantic metaphors, making the transition from dating to weather-related woes seem perfectly natural, and hilariously literal.