Fig. 2: Conceptual diagram showing the three wildfire attack mechanisms and the threat they represent depending on the distance from the house.
From: Garden design can reduce wildfire risk and drive more sustainable co-existence with wildfire

Direct flame contact represents a high risk, but only in proximity to the house. Radiant heat constitutes a high risk near the house, but quickly declines as the heat source is located away from the house. Conversely, the risk caused by firebrand attacks only slightly decline with distance.