Courniou (; ) is a commune in the Hérault department in southern France.
Courniou has a warm-summer mediterranean climate (Köppen climate classification Csb). The average annual temperature in Courniou is . The average annual rainfall is with December as the wettest month. The temperatures are highest on average in July, at around , and lowest in January, at around . The highest temperature ever recorded in Courniou was on 12 August 2003; the coldest temperature ever recorded was on 16 January 1985.