noun
lingering summer heat in autumn
Rare literary term for the residual heat felt in early autumn. In everyday language, expressions like 残暑 (ざんしょ) are far more common.
秋暑の候、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 lingering autumn heat, I hope you are all in good health and spirits.