Pollen Count & Forecast for Hiroshima

Hiroshima’s spring allergy season (February-May) is dominated by Cedar and Cypress pollen; Japanese Cedar (Cryptomeria japonica) is abundant on Mount Futaba and the northern hillsides; Japanese Cypress (Chamaecyparis obtusa) follows in late spring. Peace Memorial Park and Hijiyama Park are sources of Oak (Quercus) and Pine (Pinus) pollen. Summer (May-August) has high Grass (Poaceae) levels, originating from the Ota River banks and urban green spaces.

Coastal humidity and the city’s basin geography trap allergens between the Seto Inland Sea and surrounding mountains. Autumn and winter have high Mould (Alternaria, Cladosporium) counts; spores are common in damp leaf litter in Shukkeien Garden and shaded parklands.