ニュースNews

On April 27, 2017, JMC released its 13th forecast of the dates when cherry blossoms will start to flower (kaika) and reach full bloom (mankai). JMC has estimated the flowering and full bloom dates for Somei Yoshino (Yoshino Cherry) trees in approximately 1,000 cherry blossom viewing locations in cities from Hokkaido to Kagoshima.
The flowering and full bloom dates for all areas are posted on the weather/disaster information site "Otenki Navigator", which can be accessed for free. JMC will provide timely updates.

Weather/disaster information site "Otenki Navigator" cherry blossom navigator
App "Sakura no Kimochi"(Free)（iOS / Android）
Cherry blossom flowering trends, and results of accuracy verification tests of the flowering and full-bloom forecasts.（2016 / 2015）

Prefecture	Location	Forecasted flowering date	Flowering deviation (days)	Forecasted full bloom date	Full bloom deviation (days)	Flowering date in average year
Hokkaido Region
Hokkaido	Muroran	4/29	-7	5/4	-7	5/6
Hokkaido	Hakodate	4/28	-2	4/29	-5	4/30
Hokkaido	Sapporo	4/29	-4	5/3	-4	5/3
Tohoku Region
Aomori	Aomori	4/17	-7	4/21	-8	4/24
Iwate	Morioka	4/17	-4	4/24	-1	4/21
Miyagi	Sendai	4/7	-4	4/13	-3	4/11
Akita	Akita	4/16	-2	4/19	-3	4/18
Yamagata	Yamagata	4/14	-1	4/17	-2	4/15
Fukushima	Fukushima	4/8	-1	4/12	-1	4/9
Kanto-Koushin Region
Ibaraki	Mito	4/3	1	4/10	2	4/2
Tochigi	Utsunomiya	4/3	2	4/9	1	4/1
Gunma	Maebashi	4/2	2	4/7	1	3/31
Saitama	Kumagaya	3/28	-1	4/7	2	3/29
Chiba	Choshi	4/1	1	4/10	2	3/31
Tokyo	Tokyo	3/21	-5	4/2	-1	3/26
Kanagawa	Yokohama	3/25	-1	4/6	3	3/26
Yamanashi	Kofu	3/30	3	4/9	6	3/27
Nagano	Nagano	4/14	1	4/17	0	4/13
Hokuriku Region
Niigata	Niigata	4/8	-1	4/13	-1	4/9
Toyama	Toyama	4/5	0	4/8	-2	4/5
Ishikawa	Kanazawa	4/4	0	4/8	-2	4/4
Fukui	Fukui	4/5	2	4/7	-2	4/3
Tokai Region
Gifu	Gifu	3/28	2	4/4	0	3/26
Shizuoka	Shizuoka	4/2	8	4/12	9	3/25
Aichi	Nagoya	3/28	2	4/6	3	3/26
Mie	Tsu	4/3	4	4/5	0	3/30
Kinki Region
Shiga	Hikone	4/5	3	4/9	0	4/2
Kyoto	Kyoto	3/31	3	4/7	2	3/28
Osaka	Osaka	3/30	2	4/6	1	3/28
Hyogo	Kobe	4/3	6	4/10	5	3/28
Nara	Nara	4/3	5	4/8	3	3/29
Wakayama	Wakayama	3/30	4	4/7	3	3/26
Chugoku Region
Tottori	Tottori	4/2	2	4/7	0	3/31
Shimane	Matsue	4/1	1	4/7	-1	3/31
Okayama	Okayama	4/1	3	4/7	1	3/29
Hiroshima	Hiroshima	3/27	0	4/7	3	3/27
Yamaguchi	Shimonoseki	3/29	2	4/7	2	3/27
Shikoku Region
Tokushima	Tokushima	4/3	6	4/10	5	3/28
Kagawa	Takamatsu	4/2	5	4/8	3	3/28
Ehime	Matsuyama	3/30	5	4/8	4	3/25
Kochi	Kochi	3/29	7	4/6	7	3/22
Kyushu Region
Fukuoka	Fukuoka	3/25	2	4/5	4	3/23
Saga	Saga	3/30	6	4/8	5	3/24
Nagasaki	Nagasaki	3/30	6	4/7	4	3/24
Kumamoto	Kumamoto	4/1	9	4/8	7	3/23
Oita	Oita	4/4	11	4/13	10	3/24
Miyazaki	Miyazaki	4/2	9	4/9	7	3/24
Kagoshima	Kagoshima	4/5	10	4/15	11	3/26

The flowering or full bloom is announced.

Forecasted flowering and full bloom dates for approximately 1,000 cherry blossom viewing locations across Japan

The flowering meter provides a quantitative measure of cherry trees' current progress toward flowering and full bloom, allowing you to enjoy not only the actual flowering and full bloom of cherry blossoms but also the run-up to the flowering. "Awakening level" indicates the status of cherry trees before the breaking of dormancy, "Growth level" indicates the status of cherry trees between the breaking of dormancy and flowering, and "Full bloom level" indicates the status of cherry blossoms between flowering and full bloom.

The flower buds of cherry tree blossoms are formed during the summer of the preceding year. Before they start to flower, they must enter a period of dormancy, awaken from dormancy (breaking of dormancy), and enter a period of growth. The flowering meter displays JMC's own data, which is calculated based on flowering date forecasts.
The blossom buds in the more northerly regions of Japan such as Hokkaido and Tohoku break dormancy and enter the growth stage earlier, so these regions have high awakening and Growth levels early on.

The horizontal axis indicates time (starting from autumn of the preceding year at the far left and proceeding toward the present)
The vertical axis indicates flowering meter value (the higher up, the closer to flowering).
Blossom buds in the dormant stage will have "Awakening level" of between 0 and 100%. The meter value rises as the buds are increasingly exposed to cold temperatures. When the meter value reaches 100%, it means that the buds have awakened from dormancy and entered the growth stage. Blossom buds in the growth stage have "Growth level" of between 0 and 100%. The meter value rises as the temperature gets higher. As a rule, a meter value of 100% means that cherry blossoms have begun to flower.

- View past flowering meter values to track the progress of cherry blossoms.
- Compare the progress of cherry blossoms with those of different areas.

Japan-wide flowering meter (Otenki Navigator)
About the flowering meter (pdf)

The flowering and full bloom dates of cherry blossoms depend on the temperature patterns from autumn of the preceding year. The buds of cherry blossoms are formed during the summer of the preceding year. Before they flower, they must go through two processes: dormancy and growth. Buds do not start growing as soon as they are formed; they first enter a period of dormancy. Dormancy allows the buds to survive the winter, with its cold weather and short days. This phenomenon is not exclusive to cherry trees. In temperate zones, many kinds of plant certain levels (between -5 and 15 degrees centigrade) during the autumn and winter period, trees awaken from their dormancy in anticipation of the approaching spring. After breaking dormancy, the buds enter the growth stage, and grow as the temperatures increase to flowering. During this stage, the higher the temperature is, the better the growth rate will be.
During dormancy, buds do not show any visible development. However, once they enter the growth stage, they will grow increasingly large as the moment of flowering draws nearer. Eventually, their tips will turn a yellowish green color. Just before they start to flower, it will be possible to make out their petals.

JMC has devised its own method for forecasting flowering and full bloom dates based on existing research on the forecasting of flowering and full bloom dates for Somei Yoshino (Yoshino Cherry) trees.
JMC estimates the flowering and full bloom dates for each area based on low temperatures during autumn and winter, cherry tree growth status, cumulative temperatures, and past data for each area.

JMC developed the flowering meter as a quantitative measure of cherry trees’ progress toward flowering and full bloom, which means that you can enjoy not only the actual flowering and full bloom of cherry blossoms but also the run-up to the flowering.
The flowering meter has three indices corresponding respectively to the three stages of cherry blossom development.
- Awakening level: This index measures dormancy. Awakening level increases as temperature gets lower, indicating progress toward the breaking of dormancy (0%=bud formation, 100%=breaking of dormancy)
- Growth level: This index measures growth. Growth level increases as temperature gets higher, indicating progress toward flowering (0%=breaking of dormancy, 100%=flowering)
- Full bloom level: This index measures the amount of flowering. Full bloom level increases as temperature gets higher, indicating progress toward full bloom (0%=flowering, 100%=full bloom)

References

- Japan Meteorological Agency, "Atarashii sakura no kaika yosō (New forecast of cherry blossom flowering dates)" in Kishōchō kaisetsu shiryō (Japan Meteorological Agency explanatory materials), No. 24, 1996.
- Yasuyuki, A., Chiaki, M., "Kyūmin kaijō o kōryoshita someiyoshino no kaikabi suitei moderu no ippanka (A generalized model to estimate flowering for cherry tree [prunus yedoensis] considering both processes of endodormancy completion and development)" in Journal of Agricultural Meteorology, 59(2), 2003, pp.167-177.
- Asakura, T., Sugiura, H., Sakamoto, D., Sugiura, T., Genma, H., "Sakura no mankaibi o kōiki de yosokusuru moderu (A universal model for predicting the full bloom date of Japanese flowering cherry" in Journal of Agricultural Meteorology, 66(4), 2010, pp.269-277.