1999: U.S. EXPERIENCES SECOND WARMEST YEAR ON RECORD;
GLOBAL TEMPERATURES CONTINUE WARMING TREND
December 13, 1999 For the calendar year 1999, NOAA projects that the United States will have experienced its second warmest year on record since 1900 with an average for 1999 of 55.7 degrees F. This follows 1998's all time record of 56.4 degrees. The values for both years exceed those of the warm decade of the 1930s. 1999 is consistent with a long-term warming trend observed in the United States (0.5 degrees C per century), with a substantial portion of the warming occurring since the mid-1970s.
NOAA expects every state except
California in 1999 to be above normal and 22 states from the
Rockies to Maine much above normal. Numerous records for warmth
were set during certain months of the year. Temperatures for
November turned out to be the warmest on record. During November,
eight states from the Northwest to the Great
Lakes were ranked as having the warmest November on record;
39 states were ranked as much above normal. Many cities set records
for the warmest temperature ever in November; one state (South
Dakota) set a state record for the warmest temperature ever recorded
in the state for the month. Other heat episodes occurred during
February (third warmest nationally) and during July and August,
when many locations in the Ohio Valley and eastern seaboard set
monthly or all time records for heat. The heat continued into
September in the Northeast, with New England states experiencing
one of the warmest Septembers on record.
Global temperatures for 1999 are expected to be the fifth warmest on record since 1880, NOAA and the World Meteorological Organization reported. Globally, the departure from the long-term average (1880-1998) was 0.42 degrees C (0.76 F).
Land temperatures continued near-record warmth (averaging 13.9 degrees C or 56.9 F; 0.79 degrees C or 1.42 F above the long term average) second only to 1998, but ocean temperatures were the lowest since 1994. Just as the warm oceans associated with El Niño last year contributed to the record high temperatures, the cooler ocean conditions in 1999 associated with La Niña helped to ameliorate what might otherwise have been an even warmer year. Although ocean temperatures were among the lowest of the past decade, they still averaged 15.5 degrees C (59.8 F) or 0.26 degrees C (0.47 F) above the long-term average.
The new data continue to confirm that the near-surface temperatures during the 20th century have been rising. A long-term temperature increase of 0.06 degrees C per decade (0.11 degrees F per decade) has occurred during the 20th century. There have been two sustained periods of warming, one beginning around 1910 and ending around 1945 (approximately 0.1 degrees C per decade), and the most recent beginning about 1976. Temperatures during the latter period of warming have increased to a rate of 0.2 degrees C/decade. This is comparable to the rates of warming projected by the Intergovernmental Panel on Climate Change to occur during the next century due to anthropogenic effects.
NOAA's values for 1999 include an estimate for global temperatures for December. Updated values for 1999 will be available on Jan. 14, 2000.
Precipitation in the United States
The United States experienced
a near-normal year for precipitation, with nationally averaged
precipitation of 30.60 inches, which was 1.05 inches below average.
Although the national value was not unusual, there were significant
regional variations. The year began on a wet note in the eastern
United States; however, a dry spell that became established in
April led to record-setting growing season dryness throughout
the Ohio Valley and Northeast. This was the driest or second
driest April-July period in all states from West Virginia to
Maine. For the 12-month period from September 1998-August 1999,
most of these states experienced either record or near-record
dryness. The drought was followed by record-setting rainfall
as two hurricanes traversed
the eastern seaboard in September. States from North Carolina
to Maine experienced a record or near-record wet September and
numerous locations reported their heaviest 24-hour precipitation,
wettest September or wettest any month on record.