the world > the earth > weather and the atmosphere > weather > wet weather > [adjective] > wet (of weather, place, or time) > rainy > very (3)
That pours (in various senses); esp. (of rain) that is falling heavily.
to rain cats and dogs: to rain very heavily. Also attributive, raining heavily. Similarly to blow (also pour) cats and dogs.
Like a torrent in rapidity or violence; torrent-like; rushing; falling in torrents, as rain.