During the dry season, when game viewing is at its best, animals are drawn to the Great Ruaha River and other water sources. the sand rivers (Mwagusi and the Mdonya rivers among others) which are now dry, have underground water reserves that the elephants know about, so often one can see the elephants digging holes to obtain this sweet water, which is also used by other creatures.
Ruaha National Park enjoys only one rainy season, usually from the end of November to May. The average rainfall in Ruaha varies from 500mm around the Msembe HQ area in the Rift Valley, to 800mm in the western high plateau area of the Park. Rainfall plays a huge role in the ecology of the Park which is reflected in the vegetation and the movement of animals.
The coolest time to visit Ruaha is normally from June to the end of July, when the temperatures range from max of 30c during the day dropping to as low as 8c at night. The temperature slowly increases over the next few months resulting in the hottest time, with daily highs of /- 40c and a night time low of approximately 25c, which is generally just before the rain begins to fall, in November and December.