Wildfires - September 2010


Updated: 7 October 2010

*Data are for the period August 31st–October 1st, and are from the National Interagency Fire Center.


September continued the 2010 annual trend of below normal fire activity. 2.97 million acres have burned during 2010 year-to-date, which is 4.20 million acres below average, and marks the smallest year-to-date acreage burned in the 11–year period of record. During September, the nation experienced above-normal temperatures and above-average precipitation. Heavy precipitation fell across the Mid-Atlantic as well as the Pacific Northwest and the northern Plains. Conditions tended to be dry across the central Rockies and the Southwest. Cooler than normal temperatures dominated the western Great Lakes and northern Plains states. See the national temperature and precipitation State of the Climate report for additional information on temperatures and precipitation. On September 1st, 20 large fires were burning across the United States, mostly in the Pacific Northwest. Five fires were burning in Oregon, four in Idaho, three in California, two in Montana and Oklahoma, while one fire was present in Arkansas, Wyoming, Washington, Montana, and Hawaii. By the middle of September, large fire activity was subdued. Twelve large fires were burning nationwide — two each in Colorado, Utah, Idaho, and California; one large fire was active in Washington, Nevada, New Mexico, and Florida. By September 30th, wildfire activity continued to quiet down, with six large fires — two in Utah, and one each in Florida, Colorado, Montana, and Idaho.

Twitchell Caynon Fire
Aerial photo of the Twitchell Canyon Fire
taken from the International Space Station
Source: NASA

Two high profile fires burned across Utah during September. The Twitchell Canyon Fire in central Utah was ignited by lightning on July 20th. After the fire began in Fishlake National Forest, resource managers decided to let the fire burn to control overgrowth. Dry wind conditions during September caused the fire to spread rapidly out of control and burned 44,446 acres (17,986 hectares) of conifer and juniper forests by the end of the month. Firefighters observed flames 200 feet (61m) tall. Interstates 70 and 15 were forced close due to the fire. Luckily, the fire burned in a region where there was no direct threat to populated areas. The fire was only 30 percent contained by October 1st. The Machine Gun Fire began on September 19th near Herriman, Utah, a suburb of Salt Lake City. Ammunition fire from a National Guard exercise ignited the fire, and strong winds caused it to grow rapidly. The fire burned 4,326 acres (1,750 hectares) and was fully contained by the 26th, but not before wreaking havoc in the area. At least four homes were destroyed and 5,000 people were forced to evacuate (CNN). When the fire was at its worst, nearly 440 people were fighting it, using 29 fire engines, helicopters, airplanes and bulldozers.

Fourmile Canyon Fire

Satellite image of Fourmile Canyon burn scar
Source: NASA

The Fourmile Canyon Fire in Boulder, Colorado was the costliest fire in Colorado’s history. The fire was ignited on September 6th when a home fire pit was not properly extinguished. Very windy conditions spread the fire rapidly, and it burned 6,181 acres by the time it was fully contained on the 13th. The blaze destroyed 166 homes and three other structures. Over 2,000 people in Boulder were forced to evacuate their homes. Nearly 1,000 firefighters were called to the scene to help get the fire under control. In seven days, the fire caused over $217 million in damages and cost another $9.5 million to contain.

2010 Wildfire Statistics

(Source: NIFC)
Year–To–Date Totals as of October 1st Nationwide Number of Fires Nationwide Number of Acres Burned
10/01/2010 57,142 2,972,240
10/01/2009 70,345 5,622,843
10/01/2008 67,772 4,740,804
10/01/2007 73,256 8,227,255
10/01/2006 83,912 9,091,808
10/01/2005 53,413 8,167,090
10/01/2004 61,355 7,732,232
10/01/2003 49,397 3,190,239
10/01/2002 67,424 6,657,049
10/01/2001 67,424 6,657,049
10/01/2000 80,158 6,002,534
5–yr average
(2005 – 2009)
69,740 7,169,849
10–yr average
(2000 – 2009)
67,325 6,352,051

According to statistics from the National Interagency Fire Center (NIFC), at the end of September, the number of nationwide fires year–to–date was 57,142, which burned 2.97 million acres (1.20 million hectares) with an average of 52 acres (21 hectares) per fire. Between August 31st and October 1st, an estimated 371,397 acres (150,299 hectares) burned across the U.S., which is 58 percent below the 2000-2009 average and marked the second least September acreage burned since records began 2000. A total of 13,343 new fires were reported during the month, which is 80 percent above the 2000-2009 average and the largest number of new September fires reported since 2000. The average number of acres burned per fire was 28 (11 hectares) during September and is 77 percent below the 2000-2009 average and the least acres burned per fire in the 11-year period of record. This is consistent with the high number of fires, and the low acreage burned.

According to the U.S. Drought Monitor, during September drought conditions deteriorated across the eastern third of the country. Moderate drought spread across Louisiana, along the Gulf Coast and along the Eastern Seaboard into the Carolinas. Severe and Extreme drought developed in Alabama and Georgia where dry conditions prevailed during the month. Extreme drought also developed in the eastern panhandle of West Virginia, while Severe drought was declared in parts of New Jersey. Moderate and Severe drought spread into the Ohio River Valley, while abnormally dry conditions enveloped Pennsylvania, Ohio, and southern Michigan. Drought conditions generally improved across the central parts of the nation, with drought being alleviated in much of the upper Midwest and western Great Lakes. Drought conditions also improved across the Southern Plains where tropical moisture brought widespread heavy rainfall. Conversely, the rainfall didn’t make it far eastward, where Severe drought expanded across the Lower Mississippi River Valley. Abnormally dry conditions expanded in the central Rockies, and Moderate drought was declared along the Colorado Front Range. Moderate drought expanded slightly in northern Arizona, while the rest of the West experienced unchanged drought Conditions. In Alaska, abnormally dry conditions expanded along the state’s southern coasts. Drought conditions remained entrenched across the Hawaiian Islands, with Extreme drought expanding into the western regions of the state.

According to the U.S. Forest Service (USFS) Wildland Fire Assessment System, at the beginning of September, high fire danger was limited to the western states. The highest fire danger was occurring in northwestern New Mexico and southern California. By mid–September, high fire danger developed across parts of the Southeast and Lower Mississippi River Valley. Very high to extreme fire danger was reported across the central Rockies, the Great Basin, and southern California. On the 30th, the high fire danger in the East was limited to the Lower Mississippi River Valley. High fire danger continued across the Rockies, Great Basin, and coastal California.

According to the USFS Wildland Fire Assessment System, the beginning of September was marked by large areas of very low 10-hour and 100-hour fuel moistures. The entire eastern Seaboard, Gulf Coast, and western third of the nation had dry small fuels (10-hour fuel moistures). The upper Midwest, Mid-Mississippi River Valley, and southern plains had very moist small fuels due to an onslaught of heavy precipitation. The dry 100-hour fuel moisture had a similar spatial pattern, with the exception of high 100-hour fuel moistures along the Gulf Coast, Northeast, and the coastal Northwest. Low 1000-hour fuel moistures were confined to the western United States. The dry conditions during the first half of September across most the country led to lower 10-hour and 100-hour fuel moistures by the 15th. The Upper Midwest remained wet, where fuel moistures were high, while small and mid-size fuels moistened in the Northeast and Northwest. The spatial pattern and magnitude of 1000-hour fuel moisture remained generally unchanged by the 15th. By the end of September, significant rainfall along the East Coast brought high moistures to fuels of all sizes. In the middle part of the country, small fuels (10-hour fuel moistures) were dry and became increasingly dry moving towards the west. The driest 10-hour fuel moistures were occurring across the Great Basin. Medium and large size fuels (100-hour and 1000-hour fuel moistures) were dry across the western third of the country, with the exception of the Pacific Northwest. Across Alaska 10-hour and 100-hour fuel moistures were low across the middle and eastern parts of the state during the first half of September. By the end of the month, fuels of all sizes were moist.

According to the USFS Wildland Fire Assessment System, at the beginning of the month, high Keetch–Byram Drought Index (KBDI) values were present along the Mid-Atlantic Coast, the Southern Plains, the Lower Mississippi River Valley, and the Ohio River Valley in the east. In the West, high KBDI values were present in northern California, as well the state’s central valley, central Nevada, and southwestern Arizona. By the 15th conditions improved across the Southern Plains, where rainfall associated with tropical systems was widespread. High KBDI values were still present along the East Coast, stretching into New Jersey. High KBDI values persisted in the West, and expanded into the Pacific Northwest as well as into Utah. At the end of September, most of the high KBDI values along the east coast were eliminated, while it was perpetuated along the Gulf Coast, Lower Mississippi River Valley, and the Ohio River Valley. The high KBDI values in the West persisted. Medium to high KBDI values were reported through the entire month across the south-central coast of Alaska.


Citing This Report

NOAA National Climatic Data Center, State of the Climate: Wildfires for September 2010, published online October 2010, retrieved on April 24, 2014 from http://www.ncdc.noaa.gov/sotc/fire/2010/9.