Ouallene or Ouallen is a desert town and bordj^{[clarification needed]} in southern Algeria. The village is located in the Adrar Province to the southeast of Reggane. The bordj sits at an elevation of about 346 m (1,135 ft) above sea level and lies in the heart of the Tanezrouft, one of the hottest and driest regions in the Sahara Desert, the world's largest hot desert.

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Ouallene has a hot desert climate (Köppen climate classification BWh), with a really long, torrid summer and a brief, very warm winter, and averages just 17 millimetres (0.67 in) of rainfall per year. The excessively sunny, hot, dry climate is marked by very high temperatures and near-zero precipitation all year-long. During many months of the year, highs of 40° are common and from June to August, inclusively, highs are consistently hovering around 45° with lows rarely dropping below 30°. The annual mean temperature exceeds 28° in Ouallene.