Dead trees are hazardous and should be considered for removal immediately. The severe drought that's gripping our area has already had a negative affect on our trees and will continue to do so for several years, even if normal precipation returns soon. Many trees that were on the line between living and dying will be pushed over the edge by this heat and lack of moisture and will die. As soon as a tree stops transporting nutrients through its vascular system, it begins to weaken. The rate at which a tree becomes too brittle to safely remove depends on a variety of factors, but the process begins immediately upon death. For your safety, and the safety of the company you hire to remove a dead tree, begin the removal process as soon as possible.