The vernal equinox (or spring equinox) marks the beginning of astronomical spring.
It occurs during the month of March in the Northern Hemisphere, and during September in the Southern Hemisphere. It usually falls on March 20 or 21.
In Japan the vernal equinox is a welcome holiday as it marks the end of winter and the arrival of spring.
At the same moment that the vernal equinox occurs in one hemisphere, it is the time of the autumnal equinox in the other hemisphere.
Traditionally, the equinoxes were a time to venerate ancestors, and the two dates of the Vernal and Autumnal equinoxes became holidays celebrated in Shinto to pay respects to past members of the imperial family.
In 1948, the holiday was changed to its current form as part of post war reforms that converted religious holidays into secular holidays. The day is intended to celebrate the love of nature and living things.
In modern Japan, the day still maintains its older traditions as visiting family graves and holding family reunions is a common way of celebrating the equinox.