Spring 2024 Pollen Dispersion Forecast 3rd Report Cedar pollen starts dispersing from early February, take early measures
January 18, 2024 12:42
Today, January 18th, the Japan Weather Association announced the “Spring 2024 Pollen Dispersion Forecast (Third Report).” The 2024 spring cedar pollen will start scattering in parts of Kyushu and Kanto from early February, and will be at the same level as usual or earlier than usual. The amount of scattering is expected to be at or slightly higher than usual in many areas. If you have hay fever, take early measures.
2024: When cedar pollen starts scattering
Cedar pollen is expected to start scattering in parts of Kyushu, Shikoku, Chugoku, Tokai, and Kanto-Koshin in early February. The dispersal will start in mid-February in the Kinki region, mid-to-late February in Hokuriku and southern Tohoku, and early to mid-March in northern Tohoku. The cedar pollen season is expected to be about the same as usual or start earlier than usual.
The male flowers of Japanese cedar will break out of dormancy smoothly if it is cold in early winter, and once they wake up from dormancy, the warmer the weather, the faster they will bloom. Although temperatures have been relatively high this winter, there has been a large temperature difference, and there was a period of cold weather in the latter half of December, so it is thought that some progress has been made in breaking dormancy. Due to the high temperature in the first half of January, it was confirmed that there were some areas where cedar pollen was slightly floating. The temperature difference will continue to be large, and there will be many cold days in late January, but temperatures in February are expected to remain higher than normal. For this reason, the cedar trees will begin to bloom in February, and in early February, such as Fukuoka and Tokyo, it is expected that the flowers will begin to disperse in early February.
Please note that small amounts of pollen may fly even before it is recognized that it has started dispersing, so it is a good idea to start taking measures to prevent pollen as early as possible.
*The scattering start date is the first day on which one or more cedar pollen per square centimeter was observed for two consecutive days.
The forecast for the start of pollen dispersion announced this time is compared to the “Japan Weather Association 2024 Spring Pollen Dispersion Forecast (2nd Report)” announced on December 7, 2023, taking into account the temperature history so far this winter. From Kyushu to the Kanto region, shipping was a few days earlier.
Peak period of cedar and cypress pollen
The peak period for cedar pollen scattering will be from late February in Fukuoka, Takamatsu, and Tokyo, and from early March in Hiroshima, Osaka, Nagoya, Kanazawa, and Sendai. The peak period is expected to last from 10 days to a month. Additionally, cypress pollen peaks in many places from late March to early April. In Sendai, the amount of cypress pollen scattered is small, and no clear peak is expected to appear.
If there is a day when it suddenly becomes warm and windy, like the first blow of spring, the amount of pollen dispersed will increase all at once, and the peak period may be brought earlier. It’s a good idea to take thorough measures against pollen even before the peak of the season.
Pollen scattering amount in spring 2024 (compared to previous years)
In the spring of 2024, the amount of cedar/cypress pollen and birch pollen in Hokkaido will be at or slightly higher than usual in most areas from Kyushu to Tohoku compared to previous years (average for the past 10 years). Hokkaido is expected to have a very large number of cases.
Compared to the previous season (2023), it will be less than the previous season in many areas from Kyushu to southern Tohoku. Northern Tohoku and Hokkaido are expected to have a large number of cases.
Pollen scattering amount in spring 2024 (compared to previous season)
Compared to the previous season (2023), it will be less than the previous season in many areas from Kyushu to southern Tohoku. Northern Tohoku and Hokkaido are expected to have a large number of cases.
Pollen scattering trends in each region
Compared to previous years, pollen scattering trends in each region are 100% in Shikoku and Kanto-Koshin, which is the same as usual, in Kyushu, Chugoku, Kinki, Tokai, Hokuriku, and Tohoku, it is slightly higher at 120-140%, and in Hokkaido, it is over 200%. That’s a very high prediction. Compared to the previous season, Shikoku, Chugoku, Hokuriku, and Kanto-Koshin are expected to be low at 50-60%, Kyushu and Kinki are expected to be slightly lower at 70%, and Tokai are expected to be at 90%, the same as last season. In Tohoku, the number is high at 150%, but there are large differences depending on the region, with southern Tohoku having a low rate and northern Tohoku having a very high rate. Hokkaido is expected to have a very high rate of over 600%.
Basis for predicting pollen scattering amount
The amount of pollen scattered is greatly influenced by the weather conditions of the previous summer. In 2023, due to the intense summer heat, the weather conditions of “high temperature, high sunshine, and little rain”, which are favorable conditions for flower bud formation, have been aligned from Kyushu to Hokkaido. It is also said that the amount of pollen scattered is affected by the amount of pollen scattered in the previous spring, and tends to decrease the following year when a large amount of pollen is scattered. In 2023, the amount of pollen scattered in the spring tended to be high, so the amount of male Japanese cedar flower buds observed in the fall is reported to be lower than in the fall of 2022 in most areas.
Therefore, the amount of pollen scattered in spring 2024 will be lower than the previous season (2023) over a wide range. Still, due to last summer’s intense heat, we expect the number of cases to be at or slightly higher than usual in many areas. Northern Tohoku and Hokkaido are expected to have significantly higher levels than the previous season, as the amount of airborne particles was low in the previous season.
The pollen scatter forecast announced this time has been revised from the “Japan Weather Association 2024 Spring Pollen Dispersion Forecast (2nd report)” announced on December 7, 2023, taking into account the flower bud survey report, etc. . There are prefectures in Shikoku, Chugoku, Kinki, Kanto-Koshin, and Tohoku that tend to be about one rank lower than usual or compared to the previous season.
[About pollen types]
Hokkaido represents birch pollen scattering, and other areas represent cedar and cypress pollen scattering.
[Explanation of terms related to scattering amount]
Very high: 200% or more of the previous season (normal year)
Many: 150% or more and less than 200% of the previous season (normal year)
Slightly high: 110% or more and less than 150% of the previous season (normal year)
Same as previous season (normal year): 90% or more and less than 110% of previous season (normal year)
Slightly less: More than 70% and less than 90% of the previous season (normal year)
Low: 50% or more and less than 70% of the previous season (normal year)
Very low: less than 50% of the previous season (normal year)
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Previous season: 2023 season scattering amount
Normal year: Average value for the past 10 years (2014-2023)
[Explanation of terms related to the weather in summer 2023]
Normal year: Average value from 1991 to 2020
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2024-01-18 03:42:11
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