Slope

Fire generally moves faster uphill than downhill. Heat rising by convection preheats fuels above it, causing them to ignite more readily and burn more intensely. Even relatively gentle slopes will cause an increase in the fire’s run upslope. On steep slopes, fire will move faster uphill than down regardless of wind direction. Steep slopes can cause burning materials to shift and roll downhill. If this occurs on a fire backing downhill, it can rapidly advance fire to the next slope where fire will again be traveling rapidly upslope. Thus, fire in steep terrain can move very quickly and overrun firelines.