TCC home About TCC Site Map Contact us

Monthly Highlights on the Climate System

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

Notice: Products have been upgraded from PDF to HTML format starting from the issue of May 2025 for improved accessibility.

Highlights in June 2026

- In the tropical Pacific, positive sea surface temperature (SST) anomalies were observed on a basin-wide scale, with particularly strong positive anomalies except in parts of the western Pacific (Fig. 4). The NINO.3 index was +1.9°C (Fig. 5). Positive SST anomalies also prevailed across the North Pacific and were significant in many areas, except between 50°N and 60°N, where zonally elongated negative anomalies were observed. In the tropical Indian Ocean, positive SST anomalies dominated, except in the central part between the equator and 20°S, where negative anomalies were observed. In the western North Atlantic, significantly positive and negative SST anomalies were observed in the subtropics and mid-latitudes, respectively. Significantly positive SST anomalies were also observed in the eastern North Atlantic.
- In the tropics, convective activity was significantly enhanced over the equatorial Pacific east of 150°E. Convective activity around the equatorial dateline, as measured by outgoing longwave radiation (OLR), was the strongest for June since 1979. Convection was also enhanced over western Africa. Meanwhile, convective activity was significantly suppressed from eastern Africa to India and from the Maritime Continent to the region east of the Philippines (Fig. 6).
- In the tropical upper troposphere, pairs of anticyclonic and cyclonic anomalies straddling the equator were observed over the tropical Pacific and across the region extending from South America to Africa, respectively (Fig. 8).
- In the tropical lower troposphere, pairs of cyclonic anomalies straddling the equator were observed over the tropical Pacific. Anticyclonic anomalies were also observed east of the Philippines (Fig. 9).
- Sea-level pressure anomalies in the tropics were negative from the central to the eastern Pacific, while positive elsewhere, with significantly positive anomalies extending from the Indian Ocean to the western Pacific. The Southern Oscillation Index was -2.5 (Fig. 5).
- In the Northern Hemisphere, the polar front jet stream was significantly stronger than normal along the Arctic coast. A split-flow pattern of the polar front jet stream was observed around 45°N, resulting in significantly weaker-than-normal westerlies between 50°N and 70°N. The subtropical jet stream was located near its climatological position, except around Africa, where it was displaced southward, and over the eastern Pacific, where it was displaced northward. Westerlies were stronger than normal over the western Pacific and from North America to the Atlantic (Fig. 11).
- In the 500-hPa height field (Fig. 10), a stronger-than-normal polar vortex was located over the Arctic Ocean. In the high latitudes, significantly positive height anomalies were observed except over the Arctic Ocean and the North Atlantic. In the mid-latitudes, positive height anomalies prevailed, with significantly positive anomalies over Europe and central Eurasia, except in some regions between 40°N and 50°N.
- In the sea-level pressure (SLP) field (Fig. 12), significantly negative anomalies were observed over the Arctic Ocean, indicating the positive phase of the summer Arctic Oscillation (AO). Negative anomalies were also observed over the northern North Atlantic and the mid-latitudes of North America. Meanwhile, positive anomalies prevailed over Eurasia and the northern North Pacific, with significantly positive anomalies extending from central to eastern Siberia.
- Monthly mean temperatures were above normal in northern Japan and near normal in other regions of Japan (Fig. 1). The monthly mean surface air temperature anomaly averaged over Japan was +0.46°C. Precipitation amounts were above normal throughout Japan, except on the Sea of Japan side of eastern Japan, where they were near normal. Significantly above-normal precipitation was observed on the Pacific side of northern, eastern, and western Japan, as well as in Okinawa/Amami. Sunshine durations were below normal in most regions, except in northern Japan and on the Sea of Japan side of eastern Japan, where they were near normal. Significantly below-normal sunshine durations were observed on the Pacific side of eastern Japan.

Climate in Japan (Fig. 1):

- Monthly precipitation amounts were significantly above normal on the Pacific side of eastern/western Japan and Okinawa/Amami, and above normal on the Sea of Japan side of western Japan. Monthly sunshine durations were below normal on the Pacific side of eastern/western Japan and Okinawa/Amami. Because these regions were affected by active Baiu fronts, low-pressure systems and Typhoon JANGMI (T2606)/Typhoon MEKKHALA (T2607)/Typhoon HIGOS (T2608).
- Monthly sunshine durations were significantly above normal on the Sea of Japan side of northern Japan, and above normal on the Pacific side of northern Japan and the Sea of Japan side of eastern Japan, as the regions were frequently covered by migratory high-pressure systems in mid-June.
- Monthly precipitation amounts were significantly above normal on the Pacific side of northern Japan, and above normal on the Sea of Japan side of northern Japan, due to the frequent influence of low-pressure systems.
- Monthly mean temperature was above normal in northern Japan, due to frequent sunny days under the influence of migratory high-pressure systems in mid-June and warm-air coverage.
- The monthly anomaly of the average surface temperature over Japan was +0.46°C . On a longer time scale, the average surface temperatures have risen at a rate of about 1.45°C per century in June.

World Climate:

- The monthly anomaly of the global average surface temperature (i.e., the combined average of the near-surface air temperature over land and the SST) was +0.55°C (2nd warmest for June since 1891) (preliminary value) (Fig. 2). On a longer time scale, global average surface temperatures have risen at a rate of about 0.77°C per century in June (preliminary value).
- Extreme climate events were as follows (Fig. 3).
  - Monthly mean temperatures were extremely high from Western Siberia to eastern Central Asia, from the Philippines to Indonesia, from eastern to western Europe, in and around northeastern Canada, from southern Mexico to Colombia and in southeastern Australia.
  - Monthly precipitation amounts were extremely high from the Pacific side of northern Japan to western Japan, in and around western Kazakhstan, from the central USA to northern Mexico and in southern Australia.
  - Monthly precipitation amounts were extremely low from Lake Baikal to eastern Kazakhstan, from eastern to western Europe and along the East Coast of the USA.

Oceanographic Conditions:

- In the equatorial Pacific, positive SST anomalies were observed on a global scale, and remarkably positive anomalies east of 165°E (Fig. 4). The monthly mean SST anomaly averaged over the NINO.3 region and the SST deviation from the latest sliding 30-year mean over the region were +1.9°C (Fig. 5).
- In the North Pacific, positive SST anomalies were widely observed except for negative anomalies between 50°N and 60°N, with many areas displaying remarkably positive anomalies.
- In the South Pacific, positive SST anomalies were widely observed except for negative anomalies in the central part between 20°S and 30°S and around 60°S with many areas displaying remarkably positive anomalies.
- In the Indian Ocean, positive SST anomalies were widely observed except for negative anomalies in the central part between the equator and 20°S, with many areas displaying remarkably positive anomalies.
- In the North Atlantic, remarkably positive SST anomalies were observed between 20°N and 30°N in the western to central parts, while remarkably negative SST anomalies were observed between 40°N and 60°N. In the eastern part, remarkably positive anomalies were observed.
- In the South Atlantic, positive SST anomalies were widely observed except for negative anomalies from the equator to 30°S in the eastern part and between 20°S and 45°S in the western part, with many areas displaying remarkably positive anomalies.

Tropics:

- Convective activity was markedly suppressed from eastern Africa to India and from the Maritime Continent to the east of the Philippines, and markedly enhanced over the equatorial region between 150°E and 120°W and over western Africa (Fig. 6).
- The global distribution of convective activity anomalies exhibited a wave-number-1 pattern. The active phase of equatorial intraseasonal oscillation propagated eastward from the eastern Pacific to South America and then became indistinct (Fig. 7).
- In the upper troposphere, paired anticyclonic circulation anomalies were seen over the central Pacific, while paired cyclonic circulation anomalies were seen from South America to Africa (Fig. 8).
- In the lower troposphere, pronounced paired cyclonic circulation anomalies prevailed over the Pacific, accompanied by dominant westerly wind anomalies along the equator. Relatively anticyclonic circulation anomalies were seen east of the Philippines. Meanwhile, anticyclonic circulation anomalies were seen mainly over the Southern Hemisphere side of the Indian Ocean, corresponding to a weaker-than-normal Somali Jet. (Fig. 9).
- In the sea level pressure field, pronounced positive anomalies were seen over the western tropical Pacific and the tropical Indian Ocean, while negative anomalies prevailed over the eastern tropical Pacific. The Southern Oscillation Index value was -2.5 (Fig. 5).

Extratropics:

- In the 500-hPa height field (Fig. 10), positive anomalies were widely observed except for negative anomalies over the Arctic Ocean, around Greenland and in some regions between 40°N and 50°N, and remarkably positive anomalies were observed over Europe and Central Siberia, where blocking highs persisted.
- The polar-front jet stream was split and significantly stronger than normal along the Arctic Ocean coast and in the latitudinal band of 40-50°N over Eurasia. The subtropical jet stream was stronger and shifted northward compared to the climatological normal over the eastern Pacific and the Atlantic (Fig. 11).
- In the sea level pressure field (Fig. 12), negative anomalies were observed over the Arctic Ocean, the northern North Atlantic and across the mid-latitudes of North America, and positive anomalies prevailed over Eurasia and the North Pacific, with significant positive anomalies from central to eastern Siberia and from the Mediterranean to India through West Asia.
- In the 850-hPa temperature field (Fig. 13), the anomaly pattern closely resembled that of the 500-hPa height field except for negative temperature anomalies in the mid-latitudes from East Asia to the western North Pacific.

Zonal mean:

- In the zonal-mean zonal wind in the troposphere, the subtropical jet in the Northern Hemisphere was stronger than the climatological normal around 40°N, and the polar-front jet stream was stronger than the climatological normal around 40°N and 75°N.
- Zonal-mean temperatures in the troposphere were above normal, except north of 80°N and south of 60°S, where temperatures were below normal. Positive anomalies were particularly pronounced around 60°N and 45°S.

Supplemental information

- Climate Anomaly Table over Japan
- Extratropics in the Southern Hemisphere
- Snow in the Northern Hemisphere
- Arctic sea ice (link to the National Snow and Ice Data Center)

Fig.1 Monthly climate anomaly/ratio over Japan (June 2026) Top: temperature anomalies (degree C) Middle: precipitation ratio (%) Bottom: sunshine duration ratio (%) The base period for the normal is 1991-2020.

Fig.10 Monthly mean 500-hPa height and anomaly in the Northern Hemisphere (June 2026) The contours show 500-hPa height at intervals of 60 m. The shading indicates its anomalies. The base period for the normal is 1991-2020.	Fig.11 Monthly mean 200-hPa wind speed and vectors in the Northern Hemisphere (June 2026) The black lines show wind speed at intervals of 10 m/s. The brown lines show its normal at intervals of 20 m/s. The base period for the normal is 1991-2020.
Fig.12 Monthly mean sea level pressure and anomaly in the Northern Hemisphere (June 2026) The contours show sea level pressure at intervals of 4 hPa. The shading indicates its anomalies. The base period for the normal is 1991-2020.	Fig.13 Monthly mean 850-hPa temperature and anomaly in the Northern Hemisphere (June 2026) The contours show 850-hPa temperature at intervals of 3 degree C. The shading indicates its anomalies. The base period for the normal is 1991-2020.

Back Number

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.
The descriptions from February-2014 to April-2023 issue are based on the JRA-55 reanalysis.

Figures and Tables

Notice: Products based on JRA-3Q were updated to those with improved quality in terms of tropical cyclone analysis. OLR-related products from January 1991 are based on NOAA CPC Blended OLR (CBO).

Notice: Figures of 'Atmospheric Circulation', 'Time Cross Section', and 'Indices' have been revised with improved quality data regarding tropical cyclone analysis. (18 June 2024)

Notice: Depending on the availability of NOAA CPC Blended OLR (CBO) data, updates may be delayed or figures may be filled with gray indicating data missing.

• Explanation on the Products for Climate System Monitoring
• 5-day Mean Figures
• 10-day Mean Figures
• Monthly Mean Figures
• 3-month Mean Figures
• Time Cross Sections
• Indices
• Oceanic Figures and Tables