The progression of the pollen fronts of Cryptomeria japonica and Chamaecyparis obtusa in 2025 was monitored by tracking the first day of pollen release from these species using a Durham sampler at 78 sites between Kyushu and Hokkaido.

The C. japonica pollen front was first observed parts of northern Kyushu, western Chugoku and southern Kanto from early to late January. By mid-February, it had reached Kyushu, southern Kinki, and most of Tokai and Kanto. By late February, it had extended to most of Chugoku and Shikoku, western Kinki, most of Hokuriku and Tohoku. By early March, it had reached northeastern Shikoku, central Kinki, and parts of Hokuriku and Tokai. By mid-March, it had advanced to the northernmost area in Tohoku and, unexpectedly, parts of northern Chugoku. It ultimately reached Sapporo in Hokkaido between late March and early April.

The C. obtusa pollen front was first detected parts of southern Kanto and Tokai in early March. By mid-March, it had spread to most of Kyushu, western Chugoku, Hokuriku, Kanto and parts of northern Tohoku. By late March, it had reached most of Shikoku, Chugoku, Kinki, Hokuriku, and additional areas of Tokai and Kanto, and northern Tohoku. By early April, it had arrived at the northernmost area of Tohoku, and the western region of Hokkaido. Finally, in mid-April, the front reached a limited area along the coast of Mutu Bay in northern Tohoku.