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October 14, 1998
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SEPTEMBER 1998, WARMEST ON RECORD FOR THE U.S. In keeping with the recent global and national trends, September 1998 was the warmest such month for the U.S. and the entire globe since records began, according to NOAA's National Climatic Data Center. With a national average temperature of 69.1�F, September 1998 surpasses September 1931 (68.4�F) as the warmest such month on record, based upon preliminary data. The 1961-1990 normal temperature for the U.S. during September is 64.8�F. |
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September Temperature
Rank | State/Region | Avg.T | Normal | Dep.from Normal | Previous Record | Year |
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1 | MT | 61.9 | 54.5 | +7.4 | 61.7 | 1938 |
1 | OK | 80.2 | 72.3 | +7.9 | 79.8 | 1931 |
1 | WY | 60.1 | 54.3 | +5.8 | 60.0 | 1990 |
1 | W.N. Central | 63.7 | 56.8 | +6.9 | 62.7 | 1897 |
1 | U.S.A. | 69.1 | 64.8 | +4.3 | 68.4 | 1931 |
2 | KS | 74.8 | 67.7 | +7.1 | 76.7 | 1931 |
2 | SD | 67.0 | 60.0 | +7.0 | 68.0 | 1897 |
3 | ID | 61.3 | 55.6 | +5.7 | 62.2 | 1990 |
3 | IA | 68.6 | 62.7 | +5.9 | 70.0 | 1931 |
3 | NE | 69.6 | 62.2 | +7.4 | 69.8 | 1931 |
3 | NJ | 69.0 | 65.5 | +3.5 | 71.4 | 1961 |
3 | NM | 68.1 | 64.3 | +3.8 | 68. | 1997 |
3 | ND | 62.6 | 55.7 | +6.9 | 63.4 | 1897 |
3 | South | 79.0 | 73.6 | +5.4 | 79.5 | 1911 |
The spring and summer of 1998 over the United States has exhibited very warm conditions that are comparable to the dust bowl era of the 1930's. However, the dry conditions which persisted during the 1930's are not evident in nearly the same scale during this past summer or over the last 17 months when global temperature records have been set each month.
The accompanying figures show the areal extent of warm and cold conditions and a temperature index for the 15 month periods July 1997-September 1998, July 1933-September 1934 and July 1935 to September 1936. Note that the recent 15 month period and particulary the spring and summer months of 1998 show the warmth extending over a comparably large area as either of the 15 month periods during the 1930's. During September of 1998, 66.4% of the country was much above normal (in the upper 10 percentile.) By comparison, the warmest period for the 1930's was September, 1933 when 60.8% of the country was categorized as much above normal. Interestingly, in the 1930's there was a cold spell during the winter of 1936 which peaked in February of that year when 54.4% of the country was classifed as much below normal (lower 10 percentile.) No such spell is evident in the 1997-1998 record. |
![]() July 1997-September 1998 ![]() July 1933-September 1934 ![]() July 1935-September 1936 |
In stark contrast, between July, 1933 and September, 1934 the US was extremely dry with a peak of 45.7% of the country with much below normal precipitation. These dry conditions were partly responsible for the record warm temperatures of that period, because when the soil is wet, energy is used to evaporate water from the soil as opposed to raising the near surface air temperature. So, the dry conditions of 1933-1934 were partly responsible for the record warm temperatures of that period as less energy was used evaporating water from the soil. This makes the extreme warmth of the past two years even more remarkable as this occurred during a period of much wetter soil conditions.
![]() Percent Area U.S. with much above or much below normal precipitation, Jul'97-Sep'98 |
![]() Percent Area U.S. with much above or much below normal precipitation, July'33-Sep'34 |
YEAR-TO-DATE RANKS AS THE 2ND WARMEST, 7TH WETTEST SINCE 1895 With a national averaged temperature of 57.64�F, preliminary data suggest that the year-to-date, January-September, was the 2nd warmest such period for the United States. The warmest year on record for the year-to-date is 57.72�F recorded in 1934. The coolest such nine-month period occurred in 1912 with an national averaged temperature of 53.30�F. The 1961-1990 normal temperature for the U.S. for the year-to-date is 55.40�F.Preliminary data indicate that the year-to-date, January-September, was the 7th wettest such period since 1895. The 1998 year-to-date national averaged precipitation totaled 25.45 inches. The 1961-1990 normal for the same nine-month period is 22.68 inches. The wettest such nine-month period was 1979 with 25.87 inches while the driest such period was 1934 with 18.78 inches. |
![]() Jan-Sept State Ranks |
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Preliminary data indicate near-surface global land and ocean temperatures for the month of September 1998 established an all-time record high. Temperatures averaged nearly 1.1 deg F above the 1880-1997 long-term mean. The high temperatures were particularly evident over the land as temperatures averaged over 1.6 degrees above the long-term mean, exceeding the old record by one-half of a degree F. The surface temperatures over the ocean were cooler this September than the record last year indicative of the shift from last September's El Niño conditions to this year's La Niña. |
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SSM/I Derived Mean Temperature Anomalies September 1998 |
![]() In situ GHCN and NCEP OI blended SST Analysis - Mean Temperature Anomalies September 1998 |
The ocean surface was cooling down in September, particularly over the east equatorial Pacific and the Gulf of Alaska, where the La Niña is becoming more evident. The warmth is persisting east of the Asian continent and around Australia, which also corresponds to a La Niña signal. The persistent warmth in the north Atlantic, along with the La Niña conditions supported the numerous hurricanes that developed during the month. Generally, the globe as a whole cooled down considerably compared to last month, by about 0.08 deg.C, but still this was enough to break the previous record set just last year.
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![]() Jan-Sept Global Surface Mean Temperature Anomalies |
Near-surface global land and ocean temperatures for the period January through September 1998 established an all-time record high. Temperatures averaged more than 1.25 deg F above the 1880-1997 long-term mean. The high temperatures were particularly evident over the land as temperatures averaged nearly two degrees above the long-term mean, exceeding the old record by over one-half of a degree F. |
Satellite Derived Jan-Sept 1998 Global Temperature Anomalies |
![]() In situ GHCN and NCEP OI blended SST Analysis - Mean Temperature Anomalies Jan-Sept 1998 |
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Then very dry conditions began (May and June) which led to the outbreak of the destructive wildfires in Florida. Drought and intense heat plagued much of Texas during the summer until tropical storm Charley struck southern Texas in late August with flooding rains, resulting in at least 20 deaths in Texas and Mexico. Del Rio Texas recorded its wettest day ever on August 23, with 17.03 inches of rain from Charley's remnants, in amazing contrast to the 2.89 inches of rain received in the previous 8 1/2 months.
Texas State Records |
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Warmest April - July for Texas: 1998: Average 77.65 degrees (Record) 1925: Average 77.65 degrees (tie) |
Driest April - July for Texas: 1998: 4.46 inches (Record) 1956: 6.20 inches |
Del Rio Precipitation Extremes | |||
City | Total | Period |
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Del Rio | 20.93 inches | Aug 1998 | Wettest Month on Record |
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15.79 inches | Sep 1964 | 2nd Wettest Month on Record |
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13.71 inches | Jun 1935 | 3rd Wettest Month on Record |
Del Rio | 20.93 inches | Aug 1998 | Wettest August on Record |
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6.10 inches | Aug 1971 | 2nd Wettest August on Record |
Del Rio | 17.03 inches | Aug 23 1998 | Wettest Day on Record Any Month |
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8.79 inches | Jun 13 1935 | 2nd Wettest Day on Record |
NOAA's National Hydrologic Information Center reported 65 flood-related fatalities for January through August 1998. Fourteen of these occurred in June in the midwest and northeast as a result of heavy rains there. Many states were designated to receive federal disaster assistance during June and July. A number of counties in each state were severely affected by flooding. Examples of the heavy rains include Blue Hill, MA with 17.32 inches in June to set a record for the month, and Marion, IN with 6 inches of rain in 6 hours in early August.
City | Year | Annual Total | May | June | July | August |
San Antonio | 1998 | 36 | 1 | 10 | 21 | 4 |
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Previous Years | 33(1948) | 5(1989) | 11(1980) | 20(1980) |
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Del Rio | 1998 | 69 | 8 | 22 | 29 | 10 |
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Previous Years | 68(1951) | 9(1953) | 23(1953) | 31(1980) |
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Houston | 1998 | 24 | 0 | 2 | 14 | 8 |
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Previous Years | 32(1980) | ||||
Dallas-Fort Worth | 1998 | 56 | 3 | 8 | 28 | 12 |
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Previous Years | 69(1980) | ||||
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Previous Years | 52(1954) | ||||
College Station | 1998 | 51 | 11 | 28 | 10 |
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Previous Years | 58(1917) |
Hurricane Georges left a trail of destruction in the Caribbean region and across the southern U.S. Gulf coast. Damage estimates are in the 3-4 billion dollar range with over one billion dollars in damages across Puerto Rico alone. Extreme flooding was reported with rainfall amounts in excess of 20 to possibly 30 inches along portions of the southern U.S. Gulf coast. Mobile, Alabama received 13.0 inches of rain from the storm, which boosted the monthly total to 23.0 inches, breaking the September record of 16 inches set 100 years ago. The highest individual storm total reported thus far is Munson, Florida, which reported 25.0 inches of rain from Georges.
Hurricane Bonnie edged into North Carolina's southern coastline near Wilmington on August 26, 1998. Bonnie was the first major hurricane (Category 3) of the 1998 season, and the winds and flooding rains damaged buildings and cut off power to nearly a half-million people. Due to the slow movement of Bonnie, rainfall totals were rather high in parts of eastern North Carolina and extreme southeastern Virginia. Damages are still being tallied, but may exceed $1.0 billion.
For more information, refer to ...
SSMI Derived Products
Global Historical Climatology Network (GHCN)
The Global Temperature Anomalies
Historical precipitation and temperature ranking maps are also available on the Internet at: http://nic.fb4.noaa.gov/products/analysis_monitoring/regional_monitoring/usa.ht ml.
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.
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