Côtes de Castillon has a maritime climate, caused by the Atlantic Ocean. The warm Gulf Stream and the Gironde act as a heat regulator and temper the climate. This ensures mild winters, warm summers, and a long, sunny fall. However, the climate of Côtes de Castillon is more continental with a greater variation in temperature during the day and less rain in summer and winter.

To the great concern of the winegrower, the harvest time and the rainy season start at about the same time. If the rain is early, not all grapes will be ripe. If the rain comes late, during the harvest, the grapes may lose concentration. Statisticians have noted that, from a climate point of view, there is a pattern every three years of three good years, three bad years, and four average years. Sometimes the normally mild region is roughly reminded of its northern location. In February 1956 there was a severe frost period with temperatures below -18º C (0F). There is also always the fear that the Saint de Glace will damage the hatched vines in the first weeks of May. Like in 1991.