National Overview

On the national scale,
  • about 49 percent of the contiguous U.S. fell in the moderate to extreme drought categories (based on the Palmer Drought Index) at the end of July;
  • severe drought affected about 37 percent of the contiguous United States as of the end of July 2002, which is about the same as the 36 percent coverage at the end of June;
  • the coverage of the current (November 1999-present) national-scale drought first peaked in August 2000 at about 36% of the contiguous U.S., which was as extensive as the major droughts of the last 40 years, but not as large as the "dust bowl" droughts of the 1930s and 1950s;
  • the total drought area decreased to about 10 percent by November 2000, but has shown a general increasing trend for much of the period since then, reaching in June 2002 the peak it had first reached in August 2000 (see graph below left);
  • on a broad scale, the last two decades were characterized by unusual wetness with short periods of extensive droughts, whereas the 1930s and 1950s were characterized by prolonged periods of extensive droughts with little wetness (see graph below right);
  • although various parts of the U.S. have experienced unusually wet conditions during the last 33 months, little change occurred in the aggregate national wetness picture during much of this period;
  • the percentage of the nation severely wet has remained below about eleven percent during this period, reaching about 3 percent by the end of July 2002 (see graph below left);
  • a file containing the national monthly percent area severely dry and wet from 1900 to present is available;
  • historical temperature, precipitation, and Palmer drought data from 1895 to present for climate divisions, states, and regions in the contiguous U.S. are available at the Climate Division: Temperature-Precipitation-Drought Data page in files having names that start with "drd964x" and ending with "txt" (without the quotes).
U.S. Drought and Wet Spell Area, 1996-present
larger image 		U.S. Drought and Wet Spell Area, 1900-present
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Although some areas of the U.S. had above normal precipitation, many areas were very dry. Integrated across the nation, July 2002 precipitation averaged about normal. Twelve of the last 35 months have averaged well below the normal, while only three averaged well above normal (see graph top right). National 2001-2002 precipitation ranks:

Precipitation Ranks for the
Contiguous U.S., 2001-2002
Period Rank
Jul 53rd driest
Jun-Jul 34th driest
May-Jul 31st driest
Apr-Jul 28th driest
Mar-Jul 28th driest
Feb-Jul 16th driest
Jan-Jul 15th driest
Dec-Jul 18th driest
Nov-Jul 25th driest
Oct-Jul 24th driest
Sep-Jul 25th driest
Aug-Jul 25th driest
Click here for graphic showing U.S. Drought and Wet Spell Area, 1996-present
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Click here for graphic showing U.S. Drought and Wet Spell Area, 1900-present
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Regional Overview

July saw the continuation of very dry conditions across much of the western states, central Great Plains, and parts of the Southeast. This month brought a dry interruption to the recently wet conditions in the Northeast and a second dry month to the otherwise wet Ohio Valley. Unusually hot conditions accompanied the dryness. July was dry at most of the primary stations in Hawaii and Alaska. The last two months have had subnormal rainfall across much of Puerto Rico.

These overall conditions are evident in the following indicators:

Two other drought-related monitoring tools are the Vegetation Health Index and the Keetch-Byram Drought Index:

  • NOAA satellite observations of vegetation health from early August revealed stress on vegetation from the southwestern U.S. into the central Plains, across parts of the Midwest to Great Lakes, and in parts of the southern and northern Appalachians.
  • The USDA Forest Service uses a satellite-based vegetation health index tool to monitor the risk of wildfires. This Greenness Index for late July revealed above-average stress on vegetation across much of the West and adjoining Great Plains, as well as parts of the eastern U.S.
  • The Keetch-Byram Drought Index (KBDI) is used by the Wildland Fire Assessment System to monitor the risk of wildfires. The end-of-July KBDI showed dry conditions across parts of the West, central and southern Plains, mid-Atlantic states, and Ohio Valley. The Forest Service fire danger analysis indicated a high risk of wildfires across parts of the western U.S. into the central Plains. The fire threat conditions can change rapidly from week to week.

Western U.S. Drought

July is in the dry season for much of the West and Northwest regions, so below normal summer precipitation has less of an impact here than in the winter. However, this month marks the beginning of the wet season for the Southwest region and the northern Rockies. On a regional basis, July 2002 was drier than normal across these western areas. The combination of subnormal rainfall and hot temperatures resulted in widespread severe to extreme short-term drought. The cumulative effect of the dryness over the last several months in the Southwest has resulted in record dry seasons from May-July back to August-July. Severe to extreme long-term drought was widespread across the western U.S. Water year (October 2001-present) precipitation totals were above average in the Northwest reflecting a rainy wet season earlier, but totals dropped precipitously toward the Rockies and the Southwest.
graph showing Southwest Region precipitation departures, January 1998-present
larger image 		map showing 6-month Standardized Precipitation Index, Feb-Jul 2002
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Numerous wildfires continued across the West during July, agriculture and the cattle industry were severely impacted, and water shortages were experienced in many localities. According to govexec.com, this fire season has already seen record fire losses -- 4 million acres and more than 1,800 homes have been burned.

Seasonal (January 1-July 31) wildfire statistics, according to the National Interagency Fire Center:

As of July 31 Nationwide Number of Fires Nationwide Number of Acres Burned
2002 52,747 4,057,663
2001 49,885 1,531,121
2000 60,293 3,488,932
10-year Average 53,742 1,963,598
By State Approximate Number of Acres Burned, as of July 31, 2002
Alaska 1,047,937
Arizona 628,675
California 233,967
Colorado 381,870
Idaho 34,502
Nevada 69,113
New Mexico 298,043
Oregon 362,972
Utah 230,149
Washington 56,188

By the end of July, topsoil moisture conditions were extremely dry across much of the western U.S. According to July 28 USDA reports, 80% or more of the topsoil was short to very short in Wyoming (96%), Colorado (94%), New Mexico (81%), Utah (81%), and Oregon (80%).

Range and pasture conditions deteriorated in many areas during July. By the end of the month (according to the July 28 Weekly Weather and Crop Bulletin), conditions on 43% of the nation's pastures and rangeland were poor or very poor (compared to 31% at this time last year):

  • more than 80% of the range and pasture lands were reported in poor to very poor condition in Colorado (92%), Arizona (87%), and New Mexico (81%),
  • 75% or more poor to very poor in Wyoming (77%) and California (75%),
  • 50% or more poor to very poor in Utah (64%).
This is the halfway point in the pasture season. According to the USDA, based on data from 1995-2002, national conditions have been lower than this during only one other year, in September-October 2000.
Several western states had the driest May-July, February-July, and August-July in their 108-year record.

A detailed discussion of drought conditions is available for the following regions and states:

map showing Statewide Precipitation Ranks for February-July 2002
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Central U.S. Drought

July saw the continuation of severely dry conditions across the northern High Plains and central Plains states (see graph below left), and this was the second month of dry conditions across parts of the Ohio Valley and southern Great Lakes (see graph below right). Heavy rains brought relief to much of the southern Plains, except for the Lower Rio Grande Valley of deep south Texas, which continued to experience severe long-term drought.

graph showing West North Central Region precipitation departures, January 1998-present
larger image 		graph showing Central Region precipitation departures, January 1998-present
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By the end of July, topsoil moisture conditions were extremely dry across much of the central and northern Plains, ravaging crops in many areas. According to July 28 USDA reports, 80% or more of the topsoil was short to very short in Nebraska (94%), Kansas (87%), South Dakota (84%), and Ohio (81%).

Range and pasture conditions deteriorated in many areas during July. By the end of the month (according to the July 28 Weekly Weather and Crop Bulletin),

  • more than 80% of the range and pasture lands were reported in poor to very poor condition in Nebraska (87%),
  • 75% or more poor to very poor in South Dakota (78%),
  • 50% or more poor to very poor in Kansas (64%), North Dakota (55%), and Ohio (52%).

A detailed discussion of drought conditions is available for the following regions and states: map showing 1-month SPI, July 2002
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Eastern U.S. Drought
July saw dryness return to the Northeast region. In the Southeast, conditions averaged near normal across the region but some areas continued extremely dry. This month marked the tenth consecutive month with slightly to much below normal precipitation averaged across the Southeast.

map showing the Palmer Z Index
larger image 		graph showing Northeast Region precipitation departures, January 1998-present
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By the end of July, topsoil moisture conditions were extremely dry across much of the eastern seaboard. According to July 28 USDA reports, 80% or more of the topsoil was short to very short in Rhode Island (100%), South Carolina (87%), and Pennsylvania (82%).

Range and pasture conditions deteriorated in many areas during July. By the end of the month (according to the July 28 Weekly Weather and Crop Bulletin),

  • more than 50% of the range and pasture lands were reported in poor to very poor in South Carolina (60%), Maryland (60%), Delaware (58%), North Carolina (55%), Virginia (53%), and Pennsylvania (53%).

Severe to extreme long-term drought persisted from Long Island and southern Pennsylvania to central Georgia. The long-term deficits were so severe that four states (VA, NC, SC, GA) had the driest August-July in the 108-year record.

A detailed discussion of drought conditions is available for the following regions and states:

map showing Statewide Precipitation Ranks for July 2002
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map showing Statewide Precipitation Ranks for August-July 2002
larger image 		map showing the 24-month SPI for July 2002
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Additional Contacts:

Damage due to the drought has been summarized by NOAA and the Office of Global Programs in the Climatological Impacts section of the Climate Information Project. Crop impact information can be found at the USDA NASS (National Agricultural Statistics Service) and Weekly Weather and Crop Bulletin pages. Drought statements by local National Weather Service Offices can be found at the NWS Hydrologic Information Center. Drought threat assessments and other information can be found at NOAA's Drought Information Center. Additional drought information can be found at the National Drought Mitigation Center, the USDA's National Agricultural Library, the interim National Drought Council, and the NOAA Paleoclimatology Program. The following states have set up web pages detailing current drought conditions and/or their plans to handle drought emergencies:
Colorado - Delaware - Delaware River Basin (DE-NJ-NY-PA) - Florida Panhandle - Georgia - Hawaii - Idaho - Kentucky - Maine - Maryland - Missouri - Montana-1 - Montana-2 - Nebraska - New Jersey-1 - New Jersey-2 - New Jersey-3 - New Mexico - North Carolina - Oklahoma-1 - Oklahoma-2 - Oklahoma-3 - Oregon-1 - Oregon-2 - Pennsylvania-1 - Pennsylvania-2 - Pennsylvania-3 - South Carolina - Texas - Vermont - Virginia - Washington - Wyoming

For additional information on current and past wildfire seasons please see the National Interagency Fire Center web site or the U.S. Forest Service Fire and Aviation web site.

NCDC's Drought Recovery Page shows the precipitation required to end or ameliorate droughts and the probability of receiving the required precipitation.

Additional climate monitoring graphics can be found at the Climate Prediction Center's monitoring pages:

Drought conditions on the Canadian prairies can be found at the Agriculture and Agri-Food Canada Drought Watch page.

Citing This Report

NOAA National Centers for Environmental Information, Monthly Drought Report for July 2002, published online August 2002, retrieved on April 26, 2024 from https://www.ncei.noaa.gov/access/monitoring/monthly-report/drought/200207.