Bucketing

n.

Heard in Limerick, Kilkenny and Dublin

Raining heavily, torrential downpour.

In use

Tis bucketing down out dere now la, ye'd need a sub to cross de square!

Posh English

It is descending in rather torrential quantities out there at present, old chap, one would require a submarine to cross the town square!

Same phrase, other counties