Roughly when, roughly where
- Okinawa: January to February, and a different species.
- Tokyo and Kyoto: late March into the first week of April, in most years.
- Kanazawa, Nagano and the Alps: early to mid April.
- Tohoku — Hirosaki, Kakunodate, Kitakami: mid to late April.
- Hokkaido: late April into early May.
How the forecasts work
Private weather companies publish first-bloom and full-bloom forecasts from January and revise them weekly, based on accumulated winter and spring temperature. They are good, but a warm February or a cold March moves the date by a week in either direction.
The practical consequence: do not book non-refundable travel around a forecast issued more than a month out. Book a trip that is worth taking anyway, and treat blossom as a bonus.
If you miss it
Go north. If Kyoto has finished, Tohoku has not, and Hirosaki Castle under blossom is arguably better than anywhere in Kansai.
Or go earlier. Plum blossom in February is more fragrant, lasts longer, and draws a fraction of the crowd — Kairaku-en in Mito and Kitano Tenmangu in Kyoto are the classic sites.
Or go up. Blossom at altitude runs weeks behind the valley floor, so a mountain town will still have it when the city is bare.
Peak bloom on a grey Tuesday beats a forecast peak you built a whole trip around and missed by four days.