GoKawiilThe peak bloom date of Kyoto’s cherry trees has been written down for more than a thousand years. Stitched together, the entries form what is widely considered the longest continuous record of any natural phenomenon on Earth.
How to read it
Each pale dot is a single recorded peak: the day a designated tree in Kyoto was judged to be at full bloom that spring. The earliest entry is from 812. There are gaps — some centuries are sparse — but the record runs continuously enough that a 30-year rolling mean (the rose line) traces a coherent climate signal over the full span.
For most of the past millennium the line wandered between early and mid April. The Little Ice Age shows up as the slow drift toward later peaks from roughly the 14th to the 19th centuries. Then, starting around 1900, the line begins falling. By the late twentieth century the rolling mean has crossed below any value seen since the Heian court was making the entries by hand.
The 2026 peak fell on March 29 — more than two weeks earlier than the pre-modern average. The signal is local to one species in one city, but it is uniquely well-documented, and uniquely long.