Generally, the blooming of the sakura or cherry blossoms signals that spring has arrived. This year, Japan had an unusual amount of late snow fall which causes the sakura to bloom later. The blooming of the sakura is a big deal in Japan. The daily weather report starting around March tries to forecast on when the sakura will bloom. When they do blossom, people flock from all over Japan to see them. Every park has a season long (1-2 week) event where people camp out and party while sitting under the cherry trees. This is called hanami or flower 
viewing.
さまざまの事おもひ出す櫻かな Samazama no koto omoidasu sakura kana
How many, many things They call to mind These cherry-blossoms! -Basho
The cherry blossom is a favorite motif in Japanese culture. It is said that the beauty of the sakura is interrupted by its short life span and that the falling flower is reminiscent of a head being cut off. This imagery brings home the impermanence of life and how we are sometimes cut down in our primes. This impermanence is the driving force to live our lives in the present moment and well because we don't know how long it will last.