also: さくか
noun
last summer; summer of last year
A straightforward temporal noun referring to the summer of the previous year. Used in both spoken and written Japanese.
昨夏はとても暑かった。
Last summer was very hot.
昨夏、家族と北海道を旅行した。
Last summer, I traveled to Hokkaido with my family.
Compound of 昨 (saku, 'last') and 夏 (ka, 'summer'). The reading さっか results from a common sound change where く (ku) is reduced to っ (small tsu) before a k-row syllable.