What is the importance of "weather and the seasons" in the novel, The Witch Elm?

The weather and the seasons symbolize the emotional state of Toby and his family, and the major plot points. French structures the narrative around the four seasons, as it begins in the spring and ends the following winter. Furthermore, the first day Toby spends in Ivy House is sunny, but the investigation into Dominic’s death is accompanied mostly by rain and even harsh storms.