How was this date determined? The ancient Greek legend says that it was precisely one week before the beginning of summer. In those days, the Greeks followed an astronomical calendar and the seasons were determined due to the 23.5-degree tilt of the Earth’s rotational axis in relation to its orbit around the sun. Summer began (then and today) on June 21st. The week before is June 14th, and this was the date set.
In 2016, the Registrar at National Day Calendar proclaimed the day to be observed on June 14th, annually.