What marks the beginning or the end of a season?

The beginning of a season is often marked by specific astronomical events, such as the solstices and equinoxes, which signify changes in daylight and temperature. For example, summer begins with the summer solstice, while winter starts with the winter solstice. Conversely, the end of a season is generally defined by the transition into the next season, often influenced by climatic changes and cultural traditions. In many places, these transitions are celebrated through various festivals or observances.