JWA 2025 Spring Pollen Dispersion Forecast (Part 2)
~Pollen season in full scale from late February, peaking from early March in many places~
Press Release
On February 19, 2025, Japan Weather Association (JWA) released its report on the 2025 spring pollen dispersion forecasts at both national and prefectural levels. The forecasts cover cedar and cypress pollen nation-wide excluding Hokkaido. However, white birch pollen forecast is available for Hokkaido.
1.Start of Cedar Pollen Dispersion in 2025
The start of cedar pollen dispersion in Kyushu and Kanto has been significantly earlier than usual in some areas, while over a wide area, it is generally at the usual time or later than usual. In Tohoku, the dispersion is expected to commence either at the usual time or earlier than usual.
Cedar pollen dispersion began significantly earlier than usual in January in parts of Kyushu, Chugoku, Tokai, and Kanto. By mid-February, dispersion had started in a wide area of Kyushu and parts of Kinki to Tohoku.
Meanwhile, due to severe cold air flowing in around the beginning of February, the temperatures from Kyushu to Tokai are lower than usual until mid-February. As a result, the start of dispersion has been later than in previous years in a wide area of Chugoku and Shikoku. Additionally, due to the severe cold weather expected to continue until the first half of the last week of February, the start of dispersion is likely to be later than usual in many areas of Kinki, Tokai, and Hokuriku.
By the end of February, the prolonged cold wave is anticipated to finally end, and dispersion is expected to start in a wide area from Chugoku and Shikoku to Koshin, as well as parts of Tohoku. In Hokuriku and Tohoku, many areas are expected to enter the cedar pollen season from early to mid-March. In Tohoku, temperatures from February to March are expected to be normal or higher, and the start of dispersion is likely to be either normal or earlier than usual.
2.Peak Period of Cedar and Cypress Pollen
This year, cedar pollen concentration is expected to increase rapidly once dispersion begins and reach its peak. Fukuoka is likely to experience the peak from late February, while across a wide range of areas including Takamatsu, Hiroshima, Osaka, Nagoya, Kanazawa, Tokyo, and Sendai, the peak is expected to commence from early March. The peak period is anticipated to last for approximately 10 days and a month. Additionally, the peak for cypress pollen is expected between late March and early April and will last from about 5 days to 2 weeks. In Sendai, the cypress pollen concentration is expected to be low, with no clearly defined peak.
On days with strong winds or sudden warmer temperatures, pollen dispersion increases significantly, with some days expected to see pollen levels exceed 100 particles per square centimeter. It is advisable to regularly check pollen and weather updates, and take appropriate pollen countermeasures.
Pollen Dispersal Forecast:
For more information on pollen dispersal forecast, follow the link below;
https://www.jwa.or.jp/english/service/seasonal-news-pollen-dispersal-forecast/
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Originally released in Japanese: 2025/2/19
PDF DOWNLOAD：JWA 2025 Spring Pollen Dispersion Forecast (Part 2)
