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HOME >Climate System Monitoring > Monthly Highlights on the Climate System

Monthly Highlights on the Climate System

'Monthly Highlights on the Climate System' has been issued in PDF format since March 2007 as a monthly bulletin focusing on the monthly highlights of the monitoring results.

Notice: From 19 May 2021 onward, the products in this page are based on the new climatological normal (1991-2020 average) unless otherwise stated.

Highlights in May 2021

- The La Niña event that started in summer 2020 has terminated (see El Niño Outlook updated on 10 June 2021).
- Due to westward extension of the North Pacific Subtropical High and associated northward displacement of the Baiu-front, monthly mean temperature in Okinawa/Amami of Japan broke its highest record for May and monthly precipitation amounts were significantly above normal in western Japan.
- Monthly mean temperatures were extremely high in the region from the southern part of East Asia to the northern part of Southeast Asia and extremely low from central to northwestern Europe.
- In the equatorial Pacific, negative SST anomalies were observed in the central to eastern part.
- Convective activity was enhanced from the northwestern tropical Indian Ocean to northern India and over the latitude band of 5°N in the western Pacific, and suppressed from the Indochina Peninsula to the seas northeast of the Philippines and from the central tropical South Pacific to the Caribbean Sea.
- Corresponding to above-mentioned convective activity anomalies, the sea level pressure field showed that the North Pacific Subtropical High expanded westward over the seas south of Japan and negative anomalies were seen from northeastern China to Japan.

Full version (PDF)

The descriptions from May-2011 to April-2021 issue are based on the former climatological normal (1981-2010 average).
In the descriptions until April-2011 issue, 1979-2004 average is used as climatological normal unless otherwise stated.
The descriptions until January-2014 issue are based on the JRA-25/JCDAS datasets.

Figures and Tables

If you would like to subscribe to Monthly Highlights on the Climate System, please send an email to

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Tokyo Climate Center, Climate Prediction Division.
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