The river Lay flows southwestward through the commune and forms part of its eastern and southern borders.
Climate
Chantonnay has an oceanic climate (Köppen climate classificationCfb). The average annual temperature in Chantonnay is 12.3 °C (54.1 °F). The average annual rainfall is 876.9 mm (34.52 in) with November as the wettest month. The temperatures are highest on average in July, at around 19.9 °C (67.8 °F), and lowest in January, at around 5.4 °C (41.7 °F). The highest temperature ever recorded in Chantonnay was 41.3 °C (106.3 °F) on 27 June 2019; the coldest temperature ever recorded was −17.0 °C (1.4 °F) on 15 February 1956.
Climate data for Chantonnay (1981−2010 normals, extremes 1951−present)