During the spring, the days are warm in middle parts of the Northern Hemisphere, the northern half of the earth.
Summer follows with hot days and warm nights.
In autumn, the days become cooler, leading to the cold of winter. The four periods are called climatic seasons when based on these temperature and weather changes. In the Southern Hemisphere, the climatic seasons differ by about six months. This hemisphere has summer when the Northern Hemisphere has winter. Click here to take a quiz about the seasons.