Rain causes volcanic eruption
Weather, climate, and volcanoes interact in different ways. If the eruption is sufficiently severe, major quantities of ash and sulphur are ejected into the atmosphere, where the particles reflect the sunlight, causing a cooling of up to several degrees at ground level in the following years.
On the other hand, it also seems as if the weather can directly trigger a pending eruption, as evidenced by the active Soufrière Hills dome volcano on the island of Montserat. There, a high number of eruptions occur in connection with the heavy rain that falls in the area. The water seeps into nooks and crannies, where it evaporates in the encounter with the very hot magma. Vapour takes up more space than water, and so, the pressure inside the dome rises, sometimes making it collapse.
The seasons apparently also affect volcanoes. In the northern hemisphere, much more eruptions take place in the winter than in the summer. The physical explanation of the phenomenon has to do with the boundless quantities of water that "travel" from the northern to the southern hemisphere and back annually. The process causes a rhythmical pressure change in the magma chambers that feed volcanoes.