Autumn, which is also referred to as fall in American English, is one of the four temperate seasons. Autumn marks the transition from summer into winter and usually begins in September , in the Northern Hemisphere, or March, in the Southern Hemisphere, when the arrival of night becomes quite noticeably earlier. The equinoxes might be also expected to be in the middle of their respective seasons.

Winter is the coldest season of the year in temperate climates, between autumn and spring. At the winter solstice, the days are shortest and the nights are longest, with days lengthening as the season progresses after the solstice. Astronomically, the winter solstice, being the day of the year which has fewest hours of daylight, ought to be the middle of the season, but seasonal lag means that the coldest period normally follows the solstice by a few weeks.

Spring is one of the four temperate seasons, the transition period between winter and summer. Spring and "springtime" refer to the season, and broadly to ideas of rebirth, renewal and regrowth. The specific definition of the exact timing of "spring" varies according to local climate, cultures and customs. At the spring equinox, days are close to 12 hours long with day length increasing as the season progresses.

Summer is the warmest of the four temperate seasons, between spring and autumn. At the summer solstice, the days are longest and the nights are shortest, with day-length decreasing as the season progresses after the solstice. The date of the beginning of summer varies according to climate, culture, and tradition, but when it is summer in the southern hemisphere it is winter in the northern hemisphere, and vice versa.