The faster a fire heats up the material around it, the faster those materials can ignite. The dryness of the fuel can also affect the behavior of the fire. When the fuel is very dry, it is consumed much faster and creates a fire that is much more difficult to contain.

As a fire progresses, the heat from it dries out material as it approaches, causing moisture to evaporate. . This makes the fuel easier to ignite when the fire finally reaches it.

Fires usually travel uphill much faster than downhill. The steeper the slope, the faster the fire travels. Fires travel in the direction of the ambient wind, which usually flows uphill. Additionally, the fire is able to preheat the fuel further up the hill because the smoke and heat are rising in that direction.

The fires can also spread to homes, jump cleared areas, or even cross natural firebreaks like rivers, leading to what’s known as an “ember attack.” When high-standing plant matter (like trees) catch fire, burning twigs, leaves, and pieces of debris can be carried large distances by the wind, still aflame after traveling tens or even hundreds of feet through the air. Any small, dry, easily flammable thing that it contacts can easily catch fire, from a leaf on another tree across a body of water to the dried pine needles in a house’s rain gutters. If the fire gets too close to a major city, it becomes much more an issue of rescuing and evacuating people than it does about saving homes and preventing property damage.