[ Fire Basics : Wildfires ]
More and more people are making their homes in woodland settings, rural areas, or remote mountain sites. In these environments, residents enjoy the beauty of nature but face the very real danger of wildfire. Wildfires often begin unnoticed. They can be ignited by the careless tossing of a cigarette, an unattended campfire, or from natural causes like lightning. Combined with high risk environments impacted by drought and Santa Ana winds, wildfires can spread quickly igniting brush, trees, and homes.
Wildfires have a rapid forward rate of spread (FROS) when burning through dense, uninterrupted fuels. They can move as fast as 10.8 kilometers per hour (6.7 mph) in forests and 22 kilometers per hour (14 mph) in grasslands. Wildfires can advance tangential to the main front to form a flanking front, or burn in the opposite direction of the main front by backing.They may also spread by jumping or spotting as winds and vertical convection columns carry firebrands (hot wood embers) and other burning materials through the air over roads, rivers, and other barriers that may otherwise act as firebreaks.
For more info > http://en.wikipedia.org/wiki/Wildfire