Waw an Namus is part of the Sahara desert, one of the world's largest and driest deserts although parts of it were wetter in the past. In some parts of the Sahara it has only rained a few times during a whole century; at Waw an Namus the little precipitation mostly occurs during winter. Wind is the most important weather factor, forming ventifacts and dunes among other structures; at Waw an Namus it mostly blows from the northeast and is sometimes accompanied by dust devils south of the volcano.