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2004 was the 24th warmest year on record for the U.S. with a nationally averaged temperature of 53.5°F (11.9°C). This is 0.7°F (0.4°C) above the 1895-2003 mean. It was also the 6th wettest year on record for the nation. |
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The last five 5-year periods (2000-2004, 1999-2003, 1998-2002, 1997-2001, 1996-2000), were the warmest 5-year periods (i.e. pentads) in the last 110 years of national records, illustrating the anomalous warmth of the last decade. The 6th warmest pentad was in the 1930s (1930-34), when the western U.S. was suffering from an extended drought coupled with anomalous warmth. The warmest year on record for the U.S. was 1998, where the record warmth was concentrated in the Northeast as compared with the Northwest in 1934. Seasonal Analysis: The temperature for the 2003-2004 winter season (Dec-Feb) was near average for the nation, with cooler than average temperatures along the eastern seaboard and above average temperatures in the central U.S. Spring (March-May) was 4th warmest on record for the nation with every contiguous state except one warmer than average. Florida was the only contiguous state that remained near average. Much of that warmth was evident in March, when over 59% of the country was considered very warm relative to average, and 3 states (AZ, UT and CO) were record warm for the month. Summer (June-August) was 9th coolest in 110 years of national records, with much of the central U.S. being much cooler than average. However, western regions were warmer or much warmer than average, contrasting the cooler eastern two thirds of the country. The 2004 fall season (September-November) was 12th warmest on record, with some states in the central U.S. having record or near record statewide temperature averages. |
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More details of individual monthly and seasonal reports for 2004 can be found in NCDC's monthly and seasonal reports. |
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The adjacent figure shows the percent of the contiguous U.S. that was very warm and the percent that was very cold during each of the past 36 months. In 2004, three months (March, May, and November) averaged very warm over 20% or more of the country, with March at just under 60% of the country. Over 20% of the country was very cold in July and August though in no other month in 2004 was there a large percentage of the country affected by very cold temperatures. Very warm and very cold conditions are defined as the warmest and coldest ten percent of recorded temperatures, respectively. |
| 2004 was much warmer than average for Washington and Oregon, and Idaho, while 33 other states were warmer than average during 2004.Only Maine averaged below the long-term mean. |
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Annual* temperatures averaged across the state of Alaska in 2004 placed 4th warmest since 1918, with a record warm summer in Alaska, as was May, June, July and August. August was also the warmest month on record for the state. The record summer warmth coupled with anomalous dryness also contributed to a record wildfire season for the state. |
| Data collected by NOAA's TIROS-N polar-orbiting satellites and adjusted for time-dependent biases by NASA and the Global Hydrology and Climate Center at the University of Alabama in Huntsville, indicate that temperatures in the lower half of the atmosphere (lowest 8 km of the atmosphere) over the U.S. were cooler than the 20-year (1979-1998) average for the first time in seven years. 2004 ranks as the 11th coolest year since satellite records began in 1979. |  |
National Precipitation  |
The adjacent figure shows the percent of the contiguous U.S. that was very wet and the percent that was very dry during each of the past 36 months. During 2004, more than a tenth of the country was very dry in 3 months (March, May and September), with percentages in March exceeding 28%. In every month, except January and July the percentage area of very wet conditions exceeded ten percent, also exceeding 20% for October and November. |
| Precipitation in the United States in 2004 was characterized by persistent moderate dryness in the West and above average wetness in the South and East. This follows a record wet year in 2003 for some of the East coast. Texas had its 3rd wettest year on record, while portions of the Mid-Atlantic U.S., Tennessee Valley and Ohio Valley were also near record. |
| Multiple landfalling tropical systems contributed to the moisture in the South and East, while less than average rain and snowfall was measured in parts of the West and the far Northeast. This dearth of rain in the West, especially during spring months, exacerbated drought conditions that have been persistent for up to 5 years in some locations. Short-term drought relief came to the region, especially the Southwest in the fall, with above average rain followed by early snow. However, despite the recent rain, long-term drought remains across much the western U.S. See the NCDC annual drought summary for more information. |  |
| Thirty-four states were wetter than average from January-December, including 10 states that were much above average. Four states were drier than average. Nationally, the it was the 6th wettest year on record. Summer and fall were especially wet for the U.S., as multiple landfalling tropical storms and hurricanes brought rainfall to the South and East. It was the 4th wettest summer on record, and 3rd wettest fall for the nation. The South and Southeast regions were record wet for the 6 months ending in November and the South was also record wet for November. |
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Severe Storms| Preliminary estimates suggest there were 22 very strong to violent tornadoes (wind speeds in excess of 158 mph, category F3-F5 on the Fujita Scale) during the 2004 tornado season (March-August). This is below the long-term (1950-2001) mean of 38. A slight negative trend in very strong to violent tornadoes has been observed since 1950. |
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There were several notable storm outbreaks in 2004. These include severe thunderstorms and tornadoes in Illinois and Indiana in April and a large outbreak of tornadoes in May in the Great Plains, including an F4 tornado that virtually destroyed the town of Hallam, Nebraska. Of note this year was the number of (primarily weaker) tornadoes produced from the severe rain bands embedded in the remnants of landfalling hurricanes and tropical storms. Although the historical occurrence of weaker (F0-F2) tornadoes is difficult to measure, given vastly improved observation practices and an increased frequency of storm reports in recent decades (and therefore a tendency to record more tornadoes), preliminary indications suggest that September had the greatest number of tornadoes for any September on record. This was due to the remnants of hurricanes Frances, Ivan and Jeanne, which all affected the southeastern U.S. |
The annual summary of significant events describes these outbreaks and other severe weather for the nation over the year. NCDC's monthly pages contain additional details and graphics for each month. |
Atlantic Hurricanes The Atlantic Basin had a more active season than average in 2004 with 15 tropical storms and 9 hurricanes, including 6 major hurricanes. The average (based on data from 1944-1996) is approximately 10 named storms and 6 hurricanes, including 2-3 major hurricanes. The ACE index of hurricane activity also indicates an above average season, with a preliminary value of approximately 220 x104 knots2. An average season is anywhere from 66 x104 knots2 to 103 x104 knots2. |
| Hurricane Ivan alone produced an ACE value of 69.9 x104 knots2. Its strength and longevity contributed substantially to the cumulative seasonal activity and it holds the record (in any basin) for the greatest consecutive time (7 days) spent with windspeeds of 120 kts/138 mph or greater. After weakening back to a depression, Ivan also looped southward and then westward through the Atlantic to regenerate into a tropical storm in the Gulf of Mexico. The first named storm of the season, Alex, which brushed North Carolina in August, holds the Atlantic basin record for the strongest hurricane North of 38�N. It reached windspeeds of 105 kts (121 mph), category 3 on the Saffir-Simpson scale while north of 38�N. The only other storm to reach major hurricane status north of 38�N was Hurricane Ellen in 1973 and it reached 100 kts (115 mph). This season was also the most costly hurricane season on record ($42 billion) for the US, with 9 storms affecting its coasts. Impacts are described on NCDC's hurricane summary page. | 
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Of additional interest was the development in March of a hurricane in the South Atlantic, the only documented hurricane in that basin to impact land, and the first hurricane in the South Atlantic to be recorded in the satellite era. More details regarding the Atlantic Hurricane Season, and notable storms therein, can be found on the 2004 Hurricane page. |
Snow Season 
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The 2003/2004 snow season was generally below average cross much of the West. The early part of the 2003/2004 western snow season began with near or above normal snow amounts, however, rapid snowmelt in early spring contributed to the below average seasonal totals. Notable snow storms include: a major winter storm in December 2003 that affected the Northeast and dropped over 2 feet (60 cm) in some New England locations. Providence, RI had its greatest 24-hour snowfall on record during this storm; Charlotte, NC had its 3rd largest snowstorm on record occurring in late February. Over a foot (30 cm) of snow fell across much of the metropolitan area; and, an unsual late-season snowstorm affected Tennessee, Indiana and Kentucky on April 13th. In Jackson, TN, it was the latest measurable snowfall on record. |
More details of individual months and seasons in 2004 can be found on NCDC's monthly pages
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.
For further information, contact:
Jay Lawrimore
http://www.ncdc.noaa.gov/oa/climate/research/2004/ann/us-summary.html 
