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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 February 2026

- In the tropical Pacific, notably positive sea surface temperature (SST) anomalies were observed in the western region, while weak negative anomalies appeared along the equator in the central region, resulting in a pronounced longitudinal SST gradient (Fig. 4). The NINO.3 index was +0.1°C (Fig. 5). Significantly positive SST anomalies were also observed in the mid-latitude North Pacific and the subtropical North Atlantic.
- In the tropics, enhanced convective activity was observed from the eastern Indian Ocean to the western Pacific, with particularly intense convection over northern Australia (Fig. 6). The convectively active phase of the Madden-Julian Oscillation developed over the eastern Indian Ocean in the middle of the month and propagated eastward toward the Maritime Continent by the end of the month (Fig. 7). The global-scale divergence anomaly exhibited a wavenumber‑1 pattern, with its center located over the Maritime Continent.
- In the tropical upper troposphere, a pair of anticyclonic anomalies straddling the equator dominated the region from the Atlantic across the Indian Ocean to the western Pacific, while a pair of cyclonic anomalies straddling the equator was observed from the central to the eastern Pacific (Fig. 8). In the tropical lower troposphere, a pair of cyclonic anomalies straddling the equator was prominently observed from the Indian Ocean to the western Pacific, while a pair of anticyclonic anomalies straddling the equator was seen over the central Pacific (Fig. 9). Sea level pressure anomalies were negative over the western Pacific, while positive anomalies prevailed over the Indian Ocean and from the central to the eastern Pacific. The Southern Oscillation Index (SOI) was +1.0.
- In the Northern Hemisphere, the zonal-mean subtropical jet shifted northward relative to its climatological position, and the polar-front jet was stronger than normal along 60°N (Fig. 11).
- In the 500-hPa height field, the polar vortex split, with its centers located over northern Canada and Siberia. Positive height anomalies dominated over the Arctic Ocean (Fig. 10). Negative height anomalies extended across the mid-latitudes of the Atlantic Ocean and along 60°N over Eurasia, while positive height anomalies stretched from the mid-latitudes of Eurasia to the North Pacific, with significantly positive anomalies around the Bering Sea, where a blocking ridge developed in the latter half of the month.
- In the sea level pressure (SLP) field, a negative Arctic Oscillation pattern was observed, with positive anomalies over the Arctic Ocean and negative anomalies across the mid-latitudes, except over the North Pacific (Fig. 12). Both the Siberian High and the Aleutian Low were weaker than normal, resulting in a weak winter monsoon over Japan.
- Above-normal temperatures were observed throughout Japan and were particularly significant in northern, eastern, and western Japan (Fig. 1). The monthly anomaly of the average surface temperature over Japan was +1.87°C. Precipitation amounts were significantly below normal in Okinawa/Amami and below normal on the Sea of Japan side of eastern Japan. Sunshine durations were above normal on the Sea of Japan sides of northern, eastern, and western Japan, as well as on the Pacific side of western Japan and in Okinawa/Amami. Snowfall amounts on the Sea of Japan side of Japan were significantly below normal in northern Japan and below normal in eastern Japan.

Climate in Japan (Fig. 1):

- Monthly sunshine durations were above normal on the Sea of Japan side of northern/eastern/western Japan and on the Pacific side of western Japan and in Okinawa/Amami. The regions were less affected by the winter monsoon and frequently covered by high-pressure systems. On the other hand, in early February, strong cold air temporarily moved southward, bringing record heavy snowfall mainly on the Sea of Japan side of eastern/western Japan.
- Monthly precipitation amounts were significantly below normal in Okinawa/Amami and below normal on the Sea of Japan side of eastern Japan. Monthly snowfall amounts were significantly below normal on the Sea of Japan side of northern Japan and below normal on the Sea of Japan side of eastern Japan. The regions were less affected by low-pressure systems and the winter monsoon.
- Monthly mean temperatures were significantly above normal in northern/eastern/western Japan and above normal in Okinawa/Amami. Monthly mean temperatures were the highest in northern Japan on record for February since 1946. The regions were covered by warm air. The monthly anomaly of the average surface temperature over Japan was +1.87°C (2nd warmest for February since 1898). On a longer time scale, the average surface temperatures have risen at a rate of about 1.60°C per century in February.

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 +0.49°C (4th warmest for February since 1891) (preliminary value) (Fig. 2). On a longer time scale, global average surface temperatures have risen at a rate of about 0.86°C per century in February (preliminary value).
- Extreme climate events were as follows (Fig. 3).
  - Monthly mean temperatures were extremely high from the western part of South Asia to around the western Mediterranean Sea, in northern Mexico and from Bolivia to northern Argentina.
  - Monthly mean temperatures were extremely low from Caribbean countries to southern Mexico.
  - Monthly precipitation amounts were extremely high from the southern part of Eastern Siberia to the southern part of Central Siberia, in central Kazakhstan, from Western Russia to western Europe, in northern Colombia and in central Australia.
  - Monthly precipitation amounts were extremely low in southeastern Canada and from Bolivia to northern Argentina.

Oceanographic Conditions:

- In the equatorial Pacific, negative SST anomalies were observed in the central part, and remarkably positive SST anomalies were observed in the eastern and western parts (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 +0.1°C (Fig. 5).
- In the North Pacific and the South Pacific, remarkably positive SST anomalies were observed in a wide area from the tropics to mid-latitudes.
- In the Indian Ocean, remarkably positive SST anomalies were observed in the western part, and negative SST anomalies were observed in the eastern part of the subtropics in the Southern Hemisphere.
- In the North Atlantic, remarkably positive SST anomalies were observed from the western to central parts of the tropics and in the high-latitudes.
- In the South Atlantic, remarkably positive SST anomalies were seen in a wide area from the tropics to mid-latitudes.

Tropics:

- Convective activity was enhanced from the eastern Indian Ocean to the western Pacific and over the subtropical central Pacific, with the marked anomalies over northern Australia, and suppressed over the equatorial central Pacific and the tropical Atlantic (Fig. 6).
- The active phase of equatorial intraseasonal oscillation strengthened in amplitude over the Indian Ocean around mid-month and propagated eastward to the Maritime Continent toward the end of the month (Fig. 7).
- In the upper troposphere, anticyclonic circulation anomalies straddling the equator were seen from the Indian Ocean to the western Pacific, and cyclonic circulation anomalies straddling the equator were seen from the central to eastern Pacific. Significant anticyclonic circulation anomalies were observed over the latitude band of 30°N from the Atlantic to western East Asia (Fig. 8).
- In the lower troposphere, cyclonic circulation anomalies straddling the equator were seen from the Indian Ocean to the western Pacific, and anticyclonic circulation anomalies straddling the equator were seen over the central Pacific (Fig. 9).
- In the sea level pressure field, positive anomalies were seen from the central to eastern equatorial Pacific. Negative anomalies were seen from the Indian Ocean to western Pacific in the equator. The Southern Oscillation Index value was +1.0 (Fig. 5).

Extratropics:

- In the 500-hPa height field (Fig. 10), positive anomalies were seen from the eastern North Atlantic to the mid-latitude central North Pacific through Central Asia, over the Arctic Sea, and over western North America, and negative anomalies were seen from the western North Atlantic to southern Central Siberia through northern Europe.
- The subtropical jet stream shifted southward around China and the dateline compared to the climatological normal, and weaker than normal around Japan. The westerly jet stream over the North Atlantic was stronger than normal. The polar-front jet stream was intensified over the latitude band from 50°N to 60°N, and its southward meandering around Japan was weak (Fig. 11).
- In the sea level pressure field (Fig. 12), positive anomalies were seen over the high-latitudes and the mid-latitude North Pacific, and negative anomalies were seen over a wide area of the mid-latitudes except over the North Pacific. The Siberian High and the Aleutian Low were weaker than normal.
- In the 850-hPa temperature field (Fig. 13), positive anomalies were seen from the eastern North Atlantic to the mid-latitude central North Pacific through Central Asia and over a wide area of North America, and negative anomalies were seen from northern Europe to Central Siberia, over northwestern Canada and the western North Atlantic.
- In the stratosphere, the northward extension of the Aleutian high was enhanced, and the polar vortex displaced toward Western to Central Siberia.

Zonal mean:

- In the zonal mean zonal wind in the troposphere, the subtropical jet stream in the Northern Hemisphere shifted northward compared to the climatological normal. Westerly wind anomalies were seen around 60°N.
- The zonal mean temperatures in the troposphere were above normal except for around 70°N, with the significantly above normal around 40°N. In the Northern Hemisphere stratosphere, above-normal temperatures were seen over the high-latitudes.

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 (February 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 (February 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 (February 2026) The black lines show wind speed at intervals of 20 m/s. The brown lines show its normal at intervals of 40 m/s. The base period for the normal is 1991-2020.
Fig.12 Monthly mean sea level pressure and anomaly in the Northern Hemisphere (February 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 (February 2026) The contours show 850-hPa temperature at intervals of 4 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