noun
clear autumn weather; crisp fall day
Literary or poetic term for the clear, refreshing weather of autumn. Often used in haiku or descriptive prose.
清秋の空に雁が渡っていった。
Geese flew across the clear autumn sky.
清秋の候、皆様にはますますご清栄のこととお慶び申し上げます。
In this season of clear autumn weather, I hope you are all doing well.