Definition of summer day in English:

summer day

Pronunciation /ˌsʌmə ˈdeɪ/

noun

  • 1A day in summer, especially one characterized as long, warm, pleasant, etc.

  • 2 figurative, rare A pleasant, easy, or successful time; a high point or climax.

Origin

Late Middle English; earliest use found in John Gower (d. 1408), poet. From summer + day.