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IRI Climate Digest   February 2004

January Global Climate Summary

Climatological Background

In January, mid-summer monsoon systems are usually at their peak in the Southern Hemisphere over southern Africa, Australia and Indonesia, and South America. In the Northern Hemisphere deep winter has set in, with strong north-south temperature differences driving the mid-latitude jet stream and storm systems.

Monthly Mean Temperature (1961-1990), data from the Climate Research Unit, University of East Anglia
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Monthly Mean Precipitation (1961-1990), data from the Climate Research Unit, University of East Anglia
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Africa: Temperatures were slightly above normal in West Africa and along the East African Rift Valley.

Europe: The southwesterly flow around a weaker-than-average subtropical anticyclone in the North Atlantic brought slightly above-average temperatures to western Europe, while eastern Europe experienced slightly below-average temperatures.

Asia: Temperatures up to 5C above average were recorded across Central West Asia, from the Arctic Ocean to the Persian Gulf, and across Siberia.

Australia: A band of cooler-than-average conditions extended along the coast of the Great Australian Bight during January. Most of the rest of the continent experienced near-normal to slightly above-normal temperatures.

South America: Weakly positive temperature departures spanned South America, from tropical latitudes to the southern tip.

North America:Below-average temperatures dominated the northern tier of the continent, covering Canada and the northeastern United States. Temperatures recorded in eastern Canada and the northeastern U.S. fell within the lowest ten percent of the climatological distribution. The Southern Plains, Texas, and the southwestern states of the U.S. along the border with Mexico experienced above-average temperatures.

Temperature Difference from the 1961-1990 mean, with data from NCEP Climate Prediction Center, CAMS.
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Southern Africa: A northwest to southeast-oriented swath of southeastern Africa, touching on southern Tanzania, northern Zambia and Mozambique, Malawi and northeastern South Africa, experienced below average rainfall, while to the northeast, the heavy rains brought about by tropical cyclone Elita caused flooding in the northern tier of Madagascar.

Indonesia, Australia and the Equatorial Western Pacific: Most of the Southern Hemisphere monsoon region, from the eastern Indian Ocean across the Maritime Continent to Papua-New Guinea and the islands of the South Pacific, received below normal precipitation, with northeastern Australia the notable exception. Precipitation was also above average on the equator around the dateline, consistent with an equatorward shift of the South Pacific Convergence Zone.

South America: Heavy rains early on in the local rainy season brought widespread flooding to northeast Brazil. Heavy rains, above the 90th percentile, and flooding were also reported in southeastern Peru and Bolivia.

Precipitation Difference from 1979-1995 mean, with data from NCEP Climate Prediction Center, CAMS-OPI.
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Oceanic Conditions

Tropical Pacific: Sea surface temperature anomalies decreased slightly between December and January in some parts of the equatorial Pacific. Temperatures remained near normal to slightly above normal across most of the tropical Pacific, and the warmest temperatures remained between 0.5C and 1.5C above normal in the equatorial Pacific, generally west of the dateline. Slightly below-normal temperatures were found right along the South American coast. See the latest IRI ENSO Update for a detailed summary and outlook.

Tropical Atlantic: The Tropical Atlantic remained relatively warm during January with few changes in the magnitude of the departures from normal since last month. Relative to climatology, the warmest waters are located along the equator and along the African coast.

Indian Ocean: Warmer-than-normal sea surface conditions continued to increase in magnitude in a large area of the central Indian Ocean in January. The largest anomalies were located in the center of the basin just south of the equator. Below-average temperatures continued along the west coast of Australia.

Mid-latitudes: Sea surface temperatures strayed from normal across large portions of the extratropical waters again in January. Temperatures in the North Atlantic Ocean remained above average in general, although below-normal temperatures were found in several locations along the coast of North America. Temperatures were largely near normal or above normal in most of the South Atlantic. In the extra-tropical Indian Ocean, temperatures as high as 1.5C above normal were found in the vicinity of 90E, with cooler-than-normal conditions along the Australian coast and south of the coast of South Africa. Temperatures in the central North Pacific were generally above normal, although a mix of above-normal and below-normal temperatures were found in the seas around Japan. In the extratropical South Pacific, with the exception of below-normal conditions offshore of South America and departures in the center of the basin as large as -2C, temperatures were largely above normal.

Monthly Sea Surface Temperature Difference from the 1971-2000 mean, with data from the Environmental Modeling Center, NCEP/NOAA.
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Material for this Global Climate Summary has been extracted from the IRI Climate Data Library, the NOAA NCEP Climate Prediction Center, the Climate Diagnostics Center, and the NOAA ERL Pacific Marine Environmental Laboratories. Additional information has been obtained from the Bureau of Meteorology, Australia, and CPTEC, Brazil.

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