It's raining cats and dogs.

Meaning: 土砂降りである、大雨が降っている

For Example:

‣ You can't play soccer today. It's raining cats and dogs outside.

今日はサッカーできんね。外、土砂降りや。 ‣ I love the sound when it rains cats and dogs. It's very soothing.

大雨降っとる時の音好きやわ～。心休めてくれる。

Synonym:

It's raining heavily.

It's pouring.