In an average year, Sapporo (Hokkaido)'s autumn leaves reach peak color around October 28. For an October 11–20 trip, the chance of overlapping peak color is ~16%, and the chance of seeing at least some autumn color is ~60%.
Across October 11–20 in an average year, expect roughly 6 days of still green, and 3 days of colours turning. Leaves still mostly green — colour hasn't reached this city yet in most years.
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