Why do forest fires spread?

The Eagle Creek fire has now spread to engulf over 10,000 acres, has caused the evacuations of thousands of families, and millions of dollars in property damage. The terrain itself will take decades to recover. read more

But you asked about how it spreads. That depends on forest ecosystem and how it has been growing. In a well managed thinned forest, fire tends to go along the ground, generally doing good. If the forest is too thick and there is too much burnable material on the ground, it can get to the tops of the trees where it causes significant damage. read more

This year, over 2.8 million acres have been burned by wildfires in the US alone, as over 30 fires have raged across the dryer, more arid west of the country. Some of the fires are intentional, or prescribed. read more

Fires are very unpredictable, and that's why the situation changed so rapidly in Fort McMurray. They can spread at rates of 23 kilometres per hour when whipped up by winds for as long as fuel is available. read more