Summer afternoons often bring sudden torrential rain.
Tips
history
Echoes Du Fu's Tang poem 《白帝》: '白帝城下雨翻盆' — 'below White Emperor City the rain pours from an overturned basin'. The image of a tipped basin became the standard metaphor for downpour.
memory
倾盆 (qīng pén) literally = 'tipping a basin'. Imagine someone upending a giant washbasin overhead — that's the exact picture. The English 'bucketing down' is the closest cousin.