What is the Sahara Desert’s typical annual rainfall, measured in millimetres?

The Sahara Desert typically receives less than 100 millimetres of rainfall annually. This extremely low precipitation is a defining feature of its desert climate and helps distinguish the Sahara from semiarid regions around its margins.

Rainfall is not evenly distributed across the desert. Some areas may go for years without measurable rain, while rare storms can produce sudden flooding in dry valleys and depressions. The northern and southern edges generally receive more seasonal rainfall than the desert’s hyper-arid interior.

The Sahara is not entirely lifeless or uniformly sandy. Rocky plateaus, gravel plains, mountains, oases and temporary watercourses cover much of its area. Vegetation and animal life are concentrated where groundwater or occasional rainfall is available.

A common mix-up is treating the Sahara as the world’s largest desert overall. Antarctica is larger, but the Sahara is the largest hot desert. Its low rainfall, rather than its sand coverage alone, is central to its classification as a desert.