NOAA's National Centers for Environmental Information
Fire activity increased dramatically during June, as numerous large fires developed across the Southwest and Great Basin regions,with activity concentrated across Arizona and Nevada. As reported by the National Interagency Fire Center, over 2.1 million acres had burned across the U.S. by the end of June. The number of acres burned had surpassed 3 million as of mid–July, with fire activity spreading eastward into New Mexico and Colorado.
So far this season the most significant of the large fire activity occurred in the Southwest and southern Great Basin areas, where numerous fires continued to burn into July. The locations and extent of wildfire activity in the western U.S. through the month of June can be seen on the active and burned area map from 30 June 2005 MODIS fire detections. Significant fire activity was also observed across interior parts of Alaska during June.
Drier than normal conditions in the Southwest U.S. in late spring and summer have contributed to extremely low dead fuel moisture levels. Fine fuels remained extremely dry across the Southwest and the Great Basin, with early–July 10–hr fuel moistures below 5% across most of this region.
| As of June 30, 2005 | Nationwide Number of Fires | Nationwide Number of Acres Burned |
|---|---|---|
| 2005 | 30,217 | 2,173,746 |
| 2004 | 38,622 | 1,673,557 |
| 2003 | 27,286 | 767,018 |
| 10–year Average | 46,441 | 1,984,885 |
Medium to larger fuels dried out across the region during June (i.e. the June 30th 100–hr and June 30th 1000–hr fuel moistures), with 1000–hr fuels below 10% over most of Arizona by the end of the month. The observed fuel moistures at the end of June were a dramatic change from those measured at the end of May, at which point the area of extremely dry fuels (below 5%) was confined to the lower Colorado River valley for both the medium (May 31st 100–hr) and large (May 31st 1000–hr) fuels.
The Keetch–Byram Drought Index (KBDI), a widely used index for fire risk, had the largest potential for fire activity in the contiguous U.S. at the end of June across the southern Plains and Gulf Coast region.
The potential for large fire development was also evident in the fire danger classification at the end of June, which remained very high to extreme across most of Arizona and New Mexico.