Significant Climate Anomalies and Events in 2003

PLEASE NOTE: The ranks and temperature anomalies in this report represent the values known at the time the report was issued. The actual ranks will change as subsequent years are added to the dataset. The anomalies themselves may change slightly as missing or erroneous data is resolved. Also, in 2009, NCDC switched to ERSST version 3b (from version 2) as a component of its global surface temperature dataset. Because the versions have slightly different methodologies, the calculated temperature anomalies will differ slightly. For more information about this switch please see the Global Surface Temperature Anomalies FAQ .

Global Temperatures

Global temperatures in 2003 were 0.56°C (1.01°F) above the long-term (1880-2003) average**, ranking 2003 the second warmest year on record, which tied 2002. The warmest year on record is 1998 with an anomaly of +0.63°C (+1.13°F). Land temperatures in 2003 were 0.83°C (1.50°F) above average, ranking third in the period of record while ocean temperatures ranked as second warmest with 0.44°C (0.80°F) above the 1880-2003 mean. Global Blended Temperatures for 2003
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The map of temperature anomalies (above right) contains data from an in-situ and satellite blended data set of land and ocean temperatures. The period of record for this data set is 1988-2002, a relatively warm period compared to the base period used in the creation of the land only map of temperature anomalies below. Some minor differences in the land surface anomalies between these two maps result from the differences in base periods and data that are used to construct the two maps.

The Northern Hemisphere temperature averaged near record levels in 2003 at 0.64°C (1.15°F) above the long-term average. The Southern Hemisphere temperature also reflected the globally warmer conditions, with a positive anomaly near 0.45°C (0.81°F).

Annual anomalies in excess of +2.0°C (3.6°F) were widespread across much of North America, Asia and Europe. Additional details on temperatures throughout the world are included below.

**The 1880-2003 average combined land and ocean annual temperature is 13.9°C (56.9°F), the annually averaged land temperature for the same period is 8.5°C (47.3°F), and the long-term annually averaged sea surface temperature is 16.1°C (60.9°F).

ENSO Conditions

The year began with the equatorial Pacific Ocean in an El Niño/Southern Oscillation (ENSO) warm event. This El Niño warming began in mid-2002, and reached its maturity in November 2002 when the sea-surface temperature (SST) anomalies in the Niño 3.4 region (map of Niño regions) reached their warmest condition with a +1.54°C (+2.77°F) SST anomaly. Monthly Mean and Anomalous SSTs in the Equatorial Pacific
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Beginning in January of 2003, the anomalously warm waters in the oceanic mixed-layer in the eastern equatorial Pacific began to slowly cool. Between December 2002 and January 2003, the SST anomaly in the Niño 3.4 region decreased from +1.42°C (+2.55°F) to +0.66°C (+1.18°F). This cooling spread westward, and had affected the ocean conditions basin-wide in the February monthly mean ocean temperatures. The trend in SST anomalies was also evident in the western Pacific Ocean, reflected in the anomalies measured in the Niño 4 region. The observed cooling trend in basin-wide SSTs continued through March. The dissipation of the warm event and the transition to near-neutral ENSO conditions occurred in April, when the SST anomalies cooled to near-normal across the equatorial Pacific basin. However, the atmospheric signal lagged the ocean, with the Southern Oscillation Index (SOI) remaining negative through June (see discussion below). This trend in ocean temperatures is illustrated in the loop of Equatorial Pacific SSTs, which shows the mean and anomalous conditions across the tropical Pacific Ocean for the period December 2002 through December 2003.

Mean and Anomalous Zonal Wind Anomalies
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After the El Niño event dissipated in April, ocean surface and sub-surface temperatures began to rapidly cool. This cooling suggested the development of a La Niña cold event in the eastern and central equatorial Pacific. By the end of May, SST anomalies in the eastern and central equatorial Pacific had cooled to below -1.5 °C adjacent to the South American coast. The cold anomaly in the Niño 3.4 region was -0.63°C (-1.13°F) in May. The rapid cooling was generated by the return of easterly trade winds across the near-equatorial region, which increased equatorial upwelling in the eastern Pacific in April and May.

The colder than normal SST anomalies extended into the middle of June, but were abruptly halted when a strong westerly wind event propagated across the equatorial Pacific basin. This westerly wind event (often referred to as wind bursts) is evident in the zonal wind (U-component wind) anomalies averaged over 5-day periods in the equatorial zone. The westerly wind event was first observed in early May in the far western Pacific, and then moved eastward during June. This event generated an eastward propagating oceanic Kelvin wave that eroded the cold SST anomalies that had developed in the central and eastern Pacific during the previous two months.
Since the cessation of the cold SST anomalies in June, the equatorial Pacific region has slowly warmed. This observed warming did not develop into an El Niño by the end of 2003, but the SST anomalies have been consistently warm since July in both Niño regions (map of Niño regions). Anomalously warm SSTs have been been measured in the Niño 3.4 region for the past 6 months, and the SST anomaly had reached +0.56 °C (+1.01 °F) for the December mean. The warm oceanic conditions were also present in the sub-surface measurements from NOAA's array of moored buoys. Warmer than normal conditions were evident in the mixed-layer during December across the entire Pacific basin, although the observed ocean temperatures were well below the peak warmth observed during the 2002-2003 El Niño event. December 2003 Monthly Mean and Anomalous Mixed-Layer Temperatures
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Loop of 2003 Sub-Surface Temperatures

SOI Graph
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OLR anomalies
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The atmospheric indices measured during the latter half of 2003 in the Pacific region showed mixed signals regarding their response to the observed warming in the oceanic mixed-layer. The Southern Oscillation Index (SOI) was consistently negative during the first 6 months of 2003, which lagged the dissipation of the El Niño event. The SOI remained negative through much of the year but was strongly positive in December (see the latest SOI graph). Deep tropical convection in the western and central equatorial Pacific typically responds to the warm waters associated with ENSO warm events, and this is measured by Outgoing Longwave Radiation (OLR) across the western and central Pacific region. OLR anomalies were strongly negative in early 2003, in response to the warm SSTs during the El Niño. However, they have remained positive since April, despite the more recent warming in the equatorial Pacific Ocean observed since July (see the latest OLR Anomaly graph). Through much of the year, the atmospheric signal was mixed, with the SOI reflecting the warm SST anomalies, and the OLR remaining positive and reflecting a weak La Niña type signature. Please link to the ENSO Monitoring page for the latest ENSO conditions in the tropical Pacific.

Regional Temperatures

Global Temperature Anomalies
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Annual temperatures were above average across most land areas. The adjacent figure depicts warmer than average temperatures (for a 1961-1990 base period) that were widespread across much of the contiguous United States and Alaska, as well as most of Europe and Asia. Temperatures in these regions were 2-5°C (3.6-9.0°F) above the 1961-1990 average. This map was created using data from the Global Historical Climatology Network, a network of more than 7,000 land surface observing stations. The only widespread areas of negative anomalies were across parts of the eastern U.S., coastal areas of Australia and far western Asia where temperatures were between 1 and 3°C (1.8-5.4°F) cooler than average.
Notable temperature extremes during 2003 included a severe heatwave during summer of 2003 across Europe. Daily maximum temperatures ranged from 30-37°C (90-99°F) across France, Switzerland and the Mediterranean region, killing approximately 25,000 people. France had its warmest summer on record, and according to news reports, more than 14,000 people died of heat-related causes during the peak of the heat wave in late July and August. In North America, extreme cold winter temperatures resulted in an unusually high ice concentration across the Great Lakes. More than 90 percent of lakes Superior, Erie and Huron were frozen by March 10th, the most ice cover since February 1994. Unseasonably cold weather affected Bangladesh, India and much of Asia in January, leading to the deaths of more than 1,000 people. Average minimum temperatures were as low as 2-4°C (36-39°F), in a region where minimum temperatures are usually 12-14°C (54-57°F). In the Peruvian highlands, temperatures dropped below -20°C (-5°F) during the Southern Hemisphere winter month of July, which led to the reported deaths of more than 200 people. For more information on temperature extremes during 2003 see the annual report of Significant Events

Global Precipitation

Global Precipitation Anomalies
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Global precipitation was below the 1961-1990 average in 2003 for the third year in a row. Drought was widespread across much of eastern Australia during the first half of the year. India monsoon rainfall was 102 percent above normal, bringing relief to areas that were plagued with drought for much of 2002. Western Asia's rainfall was 80 percent above average, alleviating long-term drought conditions. In Zimbabwe, severe drought affected 900,000 people, one of Zimbabwe's worst droughts in 50 years. Other drought-affected areas included the western United States where the multi-year drought continued to ravage the region.
In contrast to drought conditions, Denver, CO had it's second biggest snowstorm on record when 31.80 inches of snow fell in March. In February, a snowstorm hit the northeastern U.S., breaking numerous 24-hour snowfall records. Heavy rainfall in mountainous regions of southwest Asia's mountain region ameliorated long-term drought conditions but caused a landslide in the village of Kara-Taryk, Kyrgyzstan killing 38 people. In Sante Fe, Argentina the reported worst flooding to occur since 1573 occurred in April of 2003. Several days of heavy rainfall caused local rivers to rise as much as 20 inches in one hour, killing 23 people and forcing the evacuation of 45,000. By early May, flooding was so severe, Sante Fe was characterized as an island. For more information about precipitation extremes during 2003 see the annual report of Significant Events.

Additional information on other notable weather events can be found in the Significant Events section of this report.


IPCC, 2001: Climate Change 2001: The Scientific Basis, Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel of Climate Change. J.T. Houghton, Y. Ding, D.J. Griggs, M. Noguer, P.J. vander Linden, X.Dai, K. Maskell, and C.A. Johnson (Eds.), Cambridge University Press, 881 pp.

NOAA's National Climatic Data Center is the world's largest active archive of weather data. The preliminary temperature and precipitation rankings are available from the center by calling: 828-271-4800.

NOAA works closely with the academic and science communities on climate-related research projects to increase the understanding of El Niño and improve forecasting techniques. NOAA's Climate Prediction Center monitors, analyzes and predicts climate events ranging from weeks to seasons for the nation. NOAA also operates the network of data buoys and satellites that provide vital information about the ocean waters, and initiates research projects to improve future climate forecasts.

Citing This Report

NOAA National Centers for Environmental Information, Monthly Global Climate Report for Annual 2003, published online January 2004, retrieved on July 20, 2024 from