In an average year, Sapporo (Hokkaido)'s cherry blossoms reach full bloom around May 6. For a May 21–31 trip, the chance of overlapping peak bloom is ~13%, and the chance of seeing at least some blossoms is ~13%.
Across May 21–31 in an average year, expect roughly 10.5 days of green hazakura (leaves). Fresh green leaves, blossoms finished. If this is your window, late-blooming yaezakura (up to ~2 weeks after) or heading north are your best moves.
Some links on this page earn us a commission from qualifying bookings, at no extra cost to you. About.