Be raining cats and dogs Definition 1 of 1Pro Tip 1/3Extreme Weather It's an expression for exceptionally heavy rainfall, not just a regular shower. We had to cancel the picnic because it was raining cats and dogs. Pro Tip 2/3Use with Caution It's informal and often used in personal conversations or creative writing. I couldn't walk the dog because it was raining cats and dogs. Pro Tip 3/3Idiomatic Imagery Imagine animals falling like rain to grasp the intensity; it's not literal. The sudden storm made it seem like it was raining cats and dogs outside!