JWA Forecasts 1.6 Times More Pollen than Usual in Spring 2025; Strong Cedar Growth Due to Intense Summer 2024 Heat to Blame

The Yomiuri Shimbun

15:56 JST, December 6, 2024

Next spring will see a nationwide average of 1.6 times more pollen in the air than in a standard year as a result of this summer’s intense heat, according to a forecast released Thursday by the Japan Weather Association.

According to the announcement, this summer’s intense heat and long sunlight hours allowed male cedar flowers — a major source of allergenic pollen — to grow well, which is expected to lead to more pollen being dispersed. The Shikoku region will see 2.1 times more pollen in the air than usual; levels will be 1.5 to 1.9 times normal in the Hokuriku, Tokai, Kinki, Chugoku and Kyushu regions; and they will be 1.3 times normal in the Kanto region, central Japan and Hokkaido. The Tohoku region is expected to see about the same level of pollen as it usually does.

Pollen dispersal is expected to start around the same times as in previous years, such as in early February in Fukuoka and mid-February in Osaka and Tokyo.