Previously the park covered an area of 10,330 sq km but in early 2008 the park was extended virtually overnight to its much larger current size of 20,226 sq km including an additional 4,500 sq km of grassland and swamp.
Ruaha isnow the largest National Park in Tanzania (the second largest park in Africa) and forms the core of a much larger ecosystem of 150,000 sq km, named the western corridor.
Ruaha’s average altitude is around 1000 metres above sea level, though elevations vary from 750 metres in the Ruaha valley to 1,868 metres at the summit of the escarpment. These peaks and hills contribute to the appealing visual landscapes of the park.
The escarpment, an offshoot of the Great Rift Valley further west, bends towards the Ruaha on either hand, enclosing, that area of the park (about one fifth) presently used by tourists, leaving the plateau beyond largely covered by Miombo and rising gradually from the escarpment, rarely visited.
The South West area of Tanzania where Ruaha is located has the lowest rainfall in Tanzania. June to December are the driest months with the focus of wildlife viewing around the drying rivers and permanent waterholes.
The average rainfall varies from 800mm per year above the escarpment to 520mm per year in the lower Ruaha valley. The rains generally fall between November and April, starting with short rains which grow in intensity. The coolest month is normally June with a daytime maximum of 30°C dropping to 15°C at night. Temperatures continue to rise throughout the year with a daytime temperature of 40°C during the day falling to only 25°C at night.