Hanami, literally "flower viewing", is the Japanese traditional custom of enjoying the beauty of flowers, "flower" in this case almost always meaning cherry blossoms (sakura) or ume blossoms. From late March to early May, sakura bloom all over Japan. The blossom forecast is announced each year by the weather bureau, 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. Hanami at night is called yozakura (lit. "night sakura"). In many places, such as Ueno Park, temporary paper lanterns are hung for the purpose of yozakura.
The practice of hanami is many centuries old. The custom is said to have started during the Nara Period (710–784) when the Chinese Tang Dynasty influenced Japan in many ways; one of which was the custom of enjoying flowers. Though it was ume blossoms that people admired in the beginning, by the Heian Period, sakura came to attract more attention. From then on, in tanka and haiku, "flowers" meant "sakura."
Hanami was first used as a term analogous to cherry blossom viewing in the Heian era novel Tale of Genji. Whilst a wisteria viewing party was also described, from this point on the terms "hanami" and "flower party" were only used to describe cherry blossom viewing.
Sakura originally was used to divine that year's harvest as well as an announcer of the rice-planting season. People believed in gods' existence inside the trees and made offerings at the root of sakura trees. Afterwards, they partook of the offering with sake. Emperor Saga of the Heian Period adopted this practice, and held flower-viewing parties with sake and feasts underneath the blossoming boughs of sakura trees in the Imperial Court in Kyoto. Poems would be written praising the delicate flowers, which were seen as a metaphor for life itself, luminous and beautiful yet fleeting and ephemeral. This was said to be the origin of hanami in Japan.