夏季

1. Origins, structure, and basic meaning

• Structure: 夏季, read かき, means the summer season.
• Basic usage: It is used to describe a facility's summer opening hours or summer temperatures on a mountain trail.
  • 夏季は開館時間を一時間延長します。

2. Common pitfalls and similar expressions

• Formality compared with 夏
  • 夏 is the everyday name of the season, while 夏季 is well suited to the summer period in notices, reports, and similar documents.