Fires burn during Namibia's severe dry season from April to October. The vast majority occurs as surface fires that spread in the grass and shrub layer. Crown fires and ground fires occur over only limited geographical areas. The amount and connectivity of the predominant grass and shrub fuel is highly variable spatially and temporally, controlled by a severe rainfall gradient oriented in an approximately SW to NE direction. This means that the most frequent, intense and extensive fires occur in the north and particularly in the northeast, while in the south and west fires rarely occur. See http://www.fao.org/docrep/006/ad653e/ad653e25.htm.