There is a competition to predict date of cherry blossoms across the world:

Market will resolve the date using the same technique as the competition: The peak bloom date of the Prunus jamasakura is determined by a local news paper in Arashiyama (Kyoto, JP). Will resolve YES if peak blossom is April 4th or earlier, otherwise will resolve NO.

The last few peak blossom dates are: 2019-04-05, 2020-04-01, 2021-03-26 (this was the earliest ever), 2022-04-01

https://www.datagraver.com/case/kyoto-cherry-blossom-full-flower-dates

 and the full historical data series is available at 

https://github.com/GMU-CherryBlossomCompetition/peak-bloom-prediction/blob/main/data/kyoto.csv

Related market with earlier prediction date