A KBDI reading of 450 means there is a deficit of 4.5 inches of ground water available to the vegatation. Factors in the index are maximum daily temperature, daily precipitation, antecedent precipitation, and annual precipitation. The fuels and ground are quite moist. Scattered patches of surface litter remain in damp areas following a fire, and the organic layer remains basically undisturbed. Fire behavior is predictable.
Fire consumes most surface litter along with a significant loss in organic soil material.
Escaped fire is difficult to control. Fire behavior is still predictable. Above 600 KBDI, fire suppression is a major problem. Near 700, understory vegatation wilts and is consumed by fire. The levels above 600 are associated with severe drought.