South Sudan - Climate

South Sudan's climate is hot with seasonal rainfall influenced by the annual shift of the Inter-Tropical Convergence Zone; rainfall is heaviest in the upland areas of the south and diminishes to the north. There are two main seasons: wet and dry. Take or give one month, the wet season begins roughly about the end of April and ends about the end of November, followed by dry season. Temperatures do not vary greatly with the season at any location; the most significant climatic variables are rainfall and the length of the dry season. Temperatures are highest at the end of the dry season when cloudless skies and dry air allow them to soar.

From January to March, the country is under the influence of the dry northeasterlies. There is practically no rainfall countrywide. By early April, the moist southwesterlies have reached southern Sudan, bringing heavy rains and thunderstorms. The far south, with only a short dry season, has uniformly high temperatures throughout the year. Yambio, close to the border with Zaire, has a nine-month rainy season (April-December) and receives an average of 1,142 millimeters of rain each year.

South Sudan can get stiflingly hot (and humid) in the summer, and April to November can be very wet indeed. The climate varies from very hot and humid in the wet season, and very hot and dry in the dry season that runs from December through April, or November to May. There are variations of course, depending on the altitude and the year. The 2011–12 dry season (which ran from October through May) was the first since South Sudan’s independence.

More mammals migrate in South Sudan than in the famous Serengeti migration. Close on two million white-eared kob antelope, tiang antelope, mongalla gazelle, elephant, buffalo and many other species, follow the grass and water from wet season to dry season as the grass recedes and then comes back.

With almost no access to irrigation, food production is largely determined by rainfall. April is the beginning of what is called "The Hunger Gap," as the previous year's food stores run thin and the next harvest is not until September. Traditionally, cow's milk provides an important energy source to tide the people over. The hunger season is a period of scarcity between harvests that runs from May to August. The Dinka farm and keep cattle to survive. From October to April South Sudan is in its dry season. During this time the Dinka rely on their cattle herding at riverside camps to graze. From May to September the rainy season transforms the landscape and allows them to grow crops in fixed settlements. The food they grow at this time must last them through the dry season too.

During the dry season, fields of six-foot-tall grass are burned, causing haze and falling ash. The dry season always brings the possibility of renewed violence and clashes. While violence continues throughout the rainy season, the dry season makes movement possible again and brings with it renewed insecurity. In the dry season (October to March), there is an increased risk of local road blocks and extortion, armed robbery and poor quality roads damaged by the previous rainy season. The dry season is the beginning of cattle rustling in some communities in South Sudan. In Jonglei in 2011 this deteriorated into inter communal violence with severe humanitarian consequences including deaths, population displacements and destruction of property. Insecurity, cattle-raiding, and inter-communal violence have increased in South Sudan since the end of the rainy season in October 2012 and the reopening of accessible roads in many parts of the country.

Roads may consist of a rough track and in many areas, not even that in rainy season. During the rainy season, many roads become impassable and it is not uncommon for vehicles to get stuck and stranded on muddy roads or for a 20-mile trip to take 90 minutes. Gumboots, or galoshes, that cover the lower legs are essential during the rainy season to keep snakes out and socks clean. Up to 60% of the country is cut off during the rainy season, meaning that road access in key locations of humanitarian response is minimal or impossible from July until December (and in some cases longer). During the dry season, pastoralist groups drive herds of cattle in search of pasture. South Sudan has no clear strategy for managing or developing dry season pastoralism.