快晴(かいせい)

快晴(かいせい) means perfectly clear, cloudless weather — stronger than just 晴(は)れ (sunny). In meteorological terms, it indicates cloud cover of 10% or less.

Forms

快(かい) (pleasant) + 晴(せい) (clear)

Weather vocabulary hierarchy

• 快晴(かいせい): perfectly clear, cloudless
• 晴(は)れ: sunny, fine weather (may have some clouds)
• 曇(くも)り: cloudy
• 雨(あめ): rain

Common collocations

• 快晴(かいせい)の空(そら) (a cloudless sky)
• 快晴(かいせい)に恵(めぐ)まれる (to be blessed with clear weather)

Usage

Often used to express satisfaction about good weather for events: 運動会(うんどうかい)の日(ひ)は快晴(かいせい)だった (the sports day was perfectly clear).