A lack of rainfall during the last month has led to dry vegetation, a prime fuel for the fires, Accuweather.com reported.
Idaho and Washington states have been especially hard hit. Spokane has received only a trace of rain in several weeks, while the Mustang Complex fire in Idaho still rages after more than a month. It has burned nearly 340,000 acres and is only 25 percent contained.
Although most of the fires are in the Northwest, the Shockey fire east of San Diego, Calif., continues to burn. It has been more than 50 percent contained, but not before it consumed nearly 20 houses.
The almost total lack of rain, light winds and the vast amounts of smoke from the fires has created air quality problems. Residents of smoky areas, particularly those with asthma or other breathing problems, are advised to be cautious when outdoors.
Forecasters said light winds should continue over the region for the next two weeks as high pressure stalls over the region. Temperatures should be at normal seasonal levels.