Hanami is the Japanese traditional custom of enjoying the transient beauty of flowers; flowers in this case almost always refer to those of the cherry or, less frequently, plum trees. From the end of March to early May, cherry trees bloom all over Japan, and around the second week of January on the island of Okinawa. The blossom forecast is announced each year by the Japan Meteorological Agency, and is watched carefully by those planning hanami as the blossoms only last a week or two.
In modern-day Japan, hanami mostly consists of having an outdoor party beneath the sakura during daytime or at night. In some contexts the Sino-Japanese term 観桜 is used instead, particularly for festivals. Hanami at night is called 夜桜. In many places such as Ueno Park temporary paper lanterns are hung for the purpose of yozakura. On the island of Okinawa, decorative electric lanterns are hung in the trees for evening enjoyment, such as on the trees ascending Mt. Yae, near Motobu Town, or at the Nakijin Castle.
A more ancient form of hanami also exists in Japan, which is enjoying the plum blossoms instead, which is narrowly referred to as 梅見. This kind of hanami is popular among older people, because they are calmer than the sakura parties, which usually involve younger people and can sometimes be very crowded and noisy.
The practice of hanami is many centuries old. The custom is said to have started during the Nara period (710–794) when it was ume blossoms that people admired in the beginning. But by the Heian period (794–1185), sakura came to attract more attention and hanami was synonymous with sakura. From then on, in both waka and haiku, "flowers" meant "sakura".
Hanami was first used as a term analogous to cherry blossom viewing in the Heian era novel The Tale of Genji. Although a wisteria viewing party was also described, the terms "hanami" and "flower party" were subsequently used only in reference to cherry blossom viewing.
Sakura was originally used to divine that year's harvest as well as announce the rice-planting season.