The traditional East Asian calendars divide a year into 24 solar terms (節氣). Lìxià (pīnyīn) or Rikka (rōmaji) (Chinese and Japanese: 立夏; Korean: 입하; Vietnamese: Lập hạ; literally: "start of summer") is the 7^th solar term. It begins when the Sun reaches the celestial longitude of 45° and ends when it reaches the longitude of 60°. It more often refers in particular to the day when the Sun is exactly at the celestial longitude of 45°. In the Gregorian calendar, it usually begins around May 5 and ends around May 21.

Lixia signifies the beginning of summer in East Asian cultures.