National Overview - August 2002


NCDC transitioned to the nClimDiv dataset on Thursday, March 13, 2014. This was coincident with the release of the February 2014 monthly monitoring report. For details on this transition, please visit our public FTP site and our U.S. Climate Divisional Database site.

Top of Page National Summer Season Temperatures - June-August 2002

National Temperature Time Series
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The graph to the left shows seasonal mean temperature averaged across the contiguous United States based on long-term data from the U.S. Historical Climatology Network (USHCN). The value for June-August 2002 (climatological summer) is estimated from preliminary Climate Division data using the first difference approach. June-August 2002 ranked as the 3rd warmest such period in the 1895 to present record after the summers of 1936 and 1934. The preliminary nationally averaged temperature for summer 2002 was 73.9° F (23.3° C) which was 1.8° F (1.0° C) above the long-term mean.

Statewide mean temperature for the June-August period was much above average for 17 states, with New Jersey and Nevada having their 2nd warmest summer on record.


Significantly above average statewide mean temperatures also occurred in 39 out of the 48 contiguous states with the remainder showing near average temperatures for the summer months. Over the June-August period, no state-averaged temperature was significantly cooler than the long-term mean. When broken down by climate division however, there are some cooler than average divisions in Montana, Maine, Texas, Mississippi and Florida, and one division in Oklahoma, as can be seen in the map to the right. Record warm temperatures averaged over the June-August period were recorded in several divisions (in New Jersey, Colorado and Nevada and a small section of eastern California).

Temperatures in Alaska were above average for the summer season. In the last 15 years, there have only been 4 summers in Alaska with below average temperatures.

The pattern of summer temperature for the contiguous U.S. corresponds quite well with height anomalies in the 500mb level of the atmosphere. Though the positive height anomalies were not large for the June-August period, they were associated with warmer than average temperatures across the mid-section of the contiguous U.S. from the Southwest and West across to the Northeast. Averaged over the summer months, there were no significant negative height anomalies and where the height anomalies were near average (the southern tier of the U.S. and Montana), so were the Statewide temperature averages.
State Temperature Ranks
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500mb height and anomalies
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Top of Page August Temperatures

National Temperature Time Series
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The graph to the left shows monthly mean temperature averaged across the contiguous United States based on long-term data from the U.S. Historical Climatology Network (USHCN). The value for 2002 is estimated from preliminary Climate Division data using the first difference approach. August 2002 ranked as the 24th warmest August in the 1895 to present record. The preliminary nationally averaged temperature was 73.7° F (23.2° C) which was 0.9° F (0.5° C) above the long-term mean. The August temperature values from 1895 through 2002 are available.

Much above average warmth occurred in 9 northeastern states in August. No statewide mean temperature records were set in August, though many states stretching from the Southwest to the Northeast (seen in the map below) were warmer or much warmer than average for the month.

New Jersey had its third warmest August on record and Rhode Island, its 4th. Cooler than average temperatures were evident in the parts of Northwest, northern Rockies and northern High Plains, and also in a few areas of the Southeast as can be seen in the map of divisional temperature (below right). Temperatures in Alaska were slightly below normal at -0.36°F (-0.2°C) relative to the period 1971-2000. The pattern of warmth and cold in the contiguous U.S. in August broadly corresponds with the mean 500mb height and anomalies chart. This shows that above normal 500mb heights existed across the Northeast and Great Lakes with the largest anomalies occurring over the Great Lakes region. The warmest monthly mean statewide temperatures were displaced slightly to the east and south of the largest positive height anomalies. Much of the warmth in the Northeast occurred during the 2nd full week of the month when daily average temperature anomalies in excess of 12°C (21.6°F) were recorded. The warmth was alleviated late on the 19th and replaced by the same cool air mass which had persisted in the northern Great Plains leading to the cooler than average monthly temperatures in that region. mean 500mb height and anomalies
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State Temperature Ranks
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Regional Temperature Ranks for the
Contiguous U.S., August 2002
Region Rank
Northeast 99th coldest
East North Central 61st coldest
Central 90th coldest
Southeast 75th coldest
West North Central 43rd coldest
South 70th coldest
Southwest 90th coldest
Northwest 39th coldest
West 66th coldest
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Top of Page Temperature Departures

The map to the right, based on over 500 airport stations, shows departures from the 1971-2000 normal temperatures for August 2002. Warmer than average temperatures extended from the Southwest to the Northeast, with the largest positive departures in the contiguous U.S. (greater than 6.0° F [3.3° C]) occurring in the Northeast. The largest negative temperature anomalies were recorded in the northern Great Plains, northern Rockies and Northwest with some cooler than average temperatures also occurring along the southern coast of California and the Southeast. An animated map of daily temperature anomalies shows temperature variability throughout the month of August. National Temperature Departures
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Top of Page National Temperatures - September 2001-August 2002

National Temperature Time Series
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The graph to the left shows monthly mean temperature averaged across the contiguous United States based on long-term data from the U.S. Historical Climatology Network (USHCN). The value for the last 12 months is estimated from preliminary Climate Division data using the first difference approach. September 2001-August 2002 ranked as the 4th warmest such period in the 1895 to present record. The preliminary nationally averaged temperature was 54.4°F (12.4°C) which was 1.6°F (0.9°C) above the long-term mean.
Record warmth occurred in three states (RI, NJ and DE) averaged over the last twelve months. The pattern of state-averaged monthly temperature can be seen in the map to the right. Twenty-six other states ranked in the top ten warmest such periods. Only five states had near-average temperatures for September-August (LA, MS, AL, AR and MT). State Temperature Ranks
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Top of Page National Summer Season Precipitation - June-August 2002

National Precipitation Time Series
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The graph to the left is a time series depicting precipitation averaged across the contiguous U.S. Based upon preliminary precipitation data, June-August 2002 was slightly drier than average, ranking 30th driest in the last 108 years. This belies considerable regional variability as can be seen from the maps below.
State Precipitation Ranks
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State Precipitation Ranks
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Record summer dryness occurred in Nevada in 2002. Four other states in the Southwest (CA, AZ, UT and CO) and one in the east (OH) also received much below average precipitation with Utah having its second driest summer on record. Minnesota received record high precipitation for the June-August period, and 2 other states (ND, FL) also received much above average rainfall over the three summer months.
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Top of Page August Precipitation

National Precipitation Time Series
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The graph to the left is a time series depicting precipitation averaged across the contiguous U.S. Based upon preliminary precipitation data, August 2002 was near average, ranking 46th driest. August 2002 marks the second consecutive August which has been near average, nationally. There has been no significant trend in mean national August precipitation over the last century.
There was considerable regional variability in precipitation across the country. States in the Southwest U.S., and in the Northeast received less rainfall than average in August, while states in the northern Great Plains and the Great Lakes received above average rainfall this month. Three states, Minnesota and the Dakotas, were much wetter than average for August with a rank of 3rd wettest August on record for South Dakota. Maine was record driest for the month of August and California and Nevada had their 2nd driest August on record. Drought continued to worsen in much of the West and Southwest and despite a generally wetter than average March-June for the Northeast, dryness began to creep back into this region. While rainfall in New Mexico was near average for July, the mountains in northern New Mexico have received only 50-70% of their normal rainfall for the year according the National Weather Service in Albuquerque. Less than average monsoon season precipitation in August has continued to exacerbate the long-term drought. State Precipitation Ranks
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In North Carolina on the evening of Sunday 25th, up to 8 inches of rain fell in the area north and east of Raleigh (shown in the satellite image to the left). This led to flash flood warnings for several counties and some road closures. Heavy rain continued across eastern North Carolina through the 26th and 27th. The rain was a result of an upper level low combined with humid air across the Southeast.

Monmouth County, New Jersey declared a state of emergency after storms ripped through the area on Friday 2nd of August. High winds and lightning damaged homes and property and left emergency crews clearing debris from roads and trying to restore power to around 140,000 homes. Ocean County was also affected by the storms, but damage was less severe.

Top of Page Precipitation Departures

The map to the right, based on more than 500 airport stations, shows August 2002 total precipitation as a percent of the 1971-2000 station normals. Above normal precipitation generally occurred in the northern Plains and Mississippi Valley region, with more than 190% of normal precipitation falling in parts of the upper Midwest. However, dryness extended across most of the northeast and Ohio Valley where as little as 25% of normal rainfall was recorded. Along the west coast, less than 10% of normal precipitation fell at most stations in California, Nevada, Oregon and Washington. Texas was also mostly dry except for the southeastern corner. National Precipitation Departures
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Top of Page National Precipitation - September 2001-August 2002

National Precipitation Time Series
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The graph to the left is a time series depicting precipitation averaged across the contiguous U.S. Based upon preliminary precipitation data, September-August 2002 was drier than average, ranking 29th driest in the last 108 years. The last 3 September-August periods have averaged below the long term mean precipitation.
Record dryness occurred in 6 states (NV, UT, CO, AZ, VA and NC) averaged over the last 12 months. The pattern of state-averaged September-August precipitation can be seen in the map to the right. Eight other states ranked in the top ten driest such periods. Five states (MN, WI, IL, IN and MI) received much above average rainfall for the 12-month period, with a record wet September-August occurring in Michigan. This is a result of a relatively persistent pattern of dryness in the west and east and excessive rainfall in the central area of the contiguous U.S. State Precipitation Ranks
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Citing This Report

NOAA National Climatic Data Center, State of the Climate: National Overview for August 2002, published online September 2002, retrieved on October 21, 2014 from http://www.ncdc.noaa.gov/sotc/national/2002/8.