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National Oceanic and Atmospheric Administration

Climate of 1998
Annual Review

National Climatic Data Center

January 12,1999

1998 Global Temperature Anomalies
1998 Global Surface Temperature Anomalies
with respect to base period 1992-1998

Contributers to this information include: NOAA's National Centers for Environmental Prediction: Climate Prediction Center, the U.S. Regional Climate Centers, the World Meteorological Organization, and other climate monitoring organizations.

1998 Warmest Year on Record

Global Mean Annual Temperature Anomalies
    Global temperatures in 1998 were the warmest in the past 119 years, since reliable instrument records began. The previous record was set in 1997. The global mean temperature in 1998 was 1.20F (0.66C) above the long-term average value of 56.9F (13.8C). This was the 20th consecutive year with an annual global mean surface temperature that exceeded the long-term average. A persistent El Niño in the first half of the year and the unprecedented warmth of the Indian Ocean contributed to this record warm year.

    Both land and sea surface temperatures were above the long-term average. Sea surface temperatures were 0.92F (0.51C) above normal, while the land surface experienced even greater warmth at 1.84F (1.02C) above normal. Tropical latitudes (30N - 30S) established a new record by a wide margin, averaging 1.84F (1C) above the long-term mean, 0.68F (0.38C) above the previous record set in 1987. The Northern Hemisphere (30N - 90N) also set a record at 2.16F (1.20C) above the long-term mean. The Southern Hemisphere (30S-90S) did not experience record heat, although temperatures averaged 0.65F (0.36C) above normal.

Regional and Seasonal Variations in Global Temperatures

    An examination of global temporal and regional temperature anomalies reveals many distinct patterns. For instance, while most of the tropical land mass and ocean surface temperatures averaged above normal, a persistent flow of air from the Indian Ocean brought relatively cool, cloudy weather to equatorial east Africa during the first half of the year. Many areas in Western Europe and North America experienced their warmest February in 100 years. In June, a record-breaking heat wave in central Russia resulted in huge fires and more than 100 deaths. Australia recorded its highest ever annual mean temperature since high-quality records began in 1910. Canada also reported one of its warmest years since 1948.

    A rapid reversal in the sea surface temperature anomaly pattern occurred in the east equatorial Pacific as warm anomalies (El Niño) transitioned to cold anomalies (La Niña) during the latter half of the year. Annual temperatures averaged below normal over northern sections of Eurasia and southern South America. The cold weather in northern Eurasia was accompanied by excessive spring and autumn snow cover. While Europe and northern Asia experienced harsh early winter conditions late in 1998, much of North America had unusually warm autumn weather. Mild conditions in eastern North America came to an abrupt end as a major arctic blast spread south across during the last two weeks of the year.

Temperatures in the United States

U.S. Mean Annual Temperature Anomalies
    The United States average temperature in 1998 was 54.62F (12.57C), which placed the year in a virtual tie with 1934 as the warmest year in records dating to 1895. The average temperature in 1934 was 54.67F (12.59C) and the third warmest year on record was 1921 with an average of 54.42F (12.46C). Several regional and seasonal records were also set throughout the year. For example, the region from the Northeast to the Great Lakes experienced the warmest January-May ever; the mild winter saved on heating and snow removal costs. The Southern Plains experienced their warmest July-September while the Far West was third warmest. From the Southern Plains to the Gulf Coast, the warmest May-November was established in 1998. The protracted summer heat wave resulted in extraordinary runs of daily temperatures 90F or hotter in several Texas and Florida cities. In contrast, California and Nevada experienced their second coolest April-June. September monthly anomalies show that nearly two-thirds of the contiguous United States was much warmer than normal.

Global Precipitation


    The 1998 global average precipitation anomaly for the land surface was 27.9 mm (1.1 in) above the 1900-1997 mean. Considerable differences were evident in precipitation departures across latitude bands with an average surplus of precipitation in the majority of Northern Hemisphere, and a deficit elsewhere.

    The 1997-98 El Niño event was one of the two strongest this century. It was associated with extremely dry conditions and devastating fires in many areas of the world, including Indonesia, eastern Russia, Brasil, Central America and Florida. The El Niño was also associated with extensive flooding in parts of northern Argentina and coastal Peru. The rapid shift to La Niña conditions at mid-year was associated with extremely heavy rains in many parts of Asia. The Indian monsoon season started later than normal, but ended with massive flooding along the Ganges River valley. Devastating late summer flooding developed on the Yangtze River in China, causing massive damage and killing more than 3000 people. The monsoon rain in the African Sahel got off to a slow start, but rainfall was greater than normal across much of the region during the latter half of the season. Although many regions of South Asia received ample rain during the summer monsoon season, the watersheds along the Mekong River of Southeast Asia and the Indus River in Pakistan also experienced extensive droughts. Summer heat and dryness plagued the Ukraine, Kazakhstan, and southern Russia. Canada also reported one of the ten driest January-November periods since records began in 1948.

Precipitation in the United States

    U.S. Annual Precipitation Anomalies

    The United States had the fifth wettest year on record in 1998 with a national average of 32.61 inches (828 mm) of precipitation. The wettest year was 1973 at 33.99 inches (863 mm). Considerable regional and seasonal variation in precipitation anomalies occurred throughout the year. For example, the Southeast and Great Lakes regions had their wettest January-March in 1998, and the West had its wettest January-June.

    A record dry April-June resulted in drought conditions from the Southern Plains to the Gulf Coast states. The spring and summer heat and drought led to massive wildfire outbreaks in Florida. Late summer and autumn rains from tropical systems helped abate the dry conditions in the South, while drought intensified in the eastern U.S. The region from the central Atlantic Coast to New York experienced the second driest July-November on record with local water restrictions implemented in many areas.

Natural Disasters

    Numerous weather-related natural disasters occurred in 1998. A January ice storm caused widespread power outages in eastern Canada and the northeastern United States. The deadliest Florida tornado outbreak on record occurred the night of February 22. A frontal system moving across the Central Plains spawned 20 tornadoes in Oklahoma on October 4, setting a national record for the most twisters ever during a single day in October. The preliminary annual count of tornadoes observed in the United States was 1239 (the average is 1186).

    El Niño contributed to the late start of the 1998 Atlantic Hurricane season which, under the influence of La Niña, ended as one of the deadliest in history with 14 named storms. Three hurricanes and four tropical storms caused $6.5 billion damage to the United States. Hurricane Georges devastated the northern Caribbean in late September. Hurricane Mitch, one of the most powerful Atlantic hurricanes on record, devastated many Central American countries in October, and resulted in a staggering loss of life. In the Pacific, October's Supertyphoon Zeb inundated the northern Philippines, Taiwan, and Japan. Only 8 days later, Supertyphoon Babs struck the Philippines, submerging parts of Manila.

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For more information, refer to ...

The Global Temperature Anomalies

SSMI Derived Products 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 or on the World Wide Web at: http:/www.ncdc.noaa.gov/ol/documentlibrary/cvb.html

Historical precipitation and temperature ranking maps are also available on the Internet at: http://nic.fb4.noaa.gov/products/analysis_monitoring/regional_monitoring/usa.html.

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. The long lead climate outlooks are available on the Internet at: http://nic.fb4.noaa.gov.

For further information, contact:

    Mike Changery
    NOAA/National Climatic Data Center
    151 Patton Avenue
    Asheville, NC 28801-5001
    fax: 828-271-4328
    email: mchangry@ncdc.noaa.gov
-or-
    David Easterling
    NOAA/National Climatic Data Center
    151 Patton Avenue
    Asheville, NC 28801-5001
    fax: 828-271-4328
    email: david.easterling@noaa.gov
-or-
    Rob Quayle
    NOAA/National Climatic Data Center
    151 Patton Avenue
    Asheville, NC 28801-5001
    fax: 828-271-4328
    email: rquayle@ncdc.noaa.gov

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