Season Facts



  • Outside the tropics there are four seasons each year. Each one lasts about three months.
  • The changes in the seasons occur because the tilt of the Earth’s axis is always the same as it circles the Sun.
  • When the Earth is on one side of the Sun, the Northern Hemisphere (half of the world) is tilted towards the Sun. It is summer in the north of the world and winter in the south.
  • As the Earth moves a quarter way round the Sun, the northern half begins to tilt away. This brings cooler autumn weather to the north and spring to the south.
  • When the Earth moves another quarter to the far side of the Sun, the Northern Hemisphere is tilted away from the Sun. It is winter in the north and summer in the south.
  • As the Earth moves three-quarters of the way round the Sun, the north begins to tilt towards the Sun again. This brings warmer weather of spring to the north, and autumn to the south.
  • Around March 21 and September 21, the night is exactly 12 hours long all over the world. These times are called the vernal (spring) equinox and the autumnal equinox.
  • The day when nights begin to get longer again is called the summer solstice. This is around June 21 in the north and December 21 in the south.
  • Many places in the tropics have just two six-month seasons: wet and dry.