Jagny-sous-Bois () is a commune in the Val-d'Oise department and ÃÂle-de-France region of France.
Jagny-sous-Bois has an oceanic climate (Köppen climate classification Cfb). The average annual temperature in Jagny-sous-Bois is . The average annual rainfall is with October 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 Jagny-sous-Bois was on 25 July 2019; the coldest temperature ever recorded was on 17 January 1985.