NOAA's National Centers for Environmental Information
Large fires – 30 September 2005
Satellite Imagery of Southern California fires
on 30 Sept. 2005
NASA MODIS image of Southern California
fires on 29 Sept. 2005
A seasonal transition in wildfire activity occurred across the U.S. during September, as the development of large fires shifted southward from the Pacific Northwest and Northern Rockies to parts of California and the Southwest. This geographical shift is typical for this time of year, as the Polar jet stream shifts southward during autumn. However, above normal precipitation during the 2004–2005 wet season enhanced the growth of brush and fine fuels across the Southwest and California, and the climatologically dry summer months have dried out these fuels and increased the potential for large fire development in these areas in early autumn.
As reported by the National Interagency Fire Center, over 8.1 million acres had burned across the U.S. by the end of September, which at present ranks the 2005 season as the second worst since 1960 for area burned. Currently the 2000 fire season remains the record year for the U.S. with over 8.4 million acres burned. Alaska had its second consecutive year with widespread wildfire activity, as over 4.4 million acres have burned across the state, while over 3.6 million acres have burned across the rest of the U.S. so far in 2005.
| As of September 30, 2005 | Nationwide Number of Fires | Nationwide Number of Acres Burned |
|---|---|---|
| 2005 | 53,413 | 8,167,090 |
| 2004 | 61,355 | 7,732,232 |
| 2003 | 49,397 | 3,955,472 |
| 10–year Average | 68,659 | 4,498,599 |
As is typical during the early fall, dead fuel moisture levels across the western U.S. and High Plains were dry during September. In particular, fine fuel moisture levels (i.e., 10–hour fuels) remained below 5% across most western states during the past month. Medium to larger fuels (i.e., the 29 September 100–hr and 29 September 1000–hr fuel moistures) were moderately dry at the end of September, especially across the Southwest and Great Basin areas.
The Keetch–Byram Drought Index (KBDI), a widely used index for fire risk, had the largest potential for wildland fire activity in the contiguous U.S. across parts of northern California and coastal Oregon. The potential for large fire development and spreading was evident in the fire danger classification on 29 September 2005, and remained high to very high across parts of the West.
For further information on drought conditions across the U.S. go to the September drought summary page.