South Sudan has a tropical climate with high temperatures year-round and a pronounced wet and dry season pattern. Average temperatures hover between 25°C and 35°C (77–95°F) across most of the country, with the hottest months typically falling between February and April before the rains arrive. What makes the climate varied, though, is the country’s geography: vast wetlands in the center, semi-arid plains in the north, and mountains in the far south that sit above 2,000 meters, each creating distinct local conditions.
Wet Season and Dry Season
South Sudan’s year splits into two broad periods. The wet season generally runs from April through November, though its exact timing depends on where you are in the country. The dry season fills the remaining months, roughly December through March, bringing hot, cloudless skies and very little rainfall.
In the southwestern areas, rains arrive earliest, with planting season starting in April and May and harvests wrapping up by August or September. Further north and in the southeast, the wet season arrives later. Farmers there plant in June and July and harvest between September and December. This staggered rainfall pattern means that while one part of the country is already deep into its growing season, another is still waiting for the first rains.
Annual rainfall varies dramatically by region. The far south, near the border with Uganda and the Democratic Republic of Congo, receives the most rain, often exceeding 1,200 mm per year. The northern areas bordering Sudan receive considerably less, sometimes below 700 mm, making them drier and more prone to drought.
Temperature Across the Country
Most of South Sudan is flat, low-lying savanna where daytime temperatures regularly reach 35–40°C (95–104°F) during the hottest weeks of the dry season. Nights offer some relief but rarely drop below 20°C (68°F) in the lowlands. During the wet season, cloud cover and rain moderate temperatures somewhat, bringing daytime highs closer to 30–33°C.
The major exception is the Imatong Mountains along the southeastern border with Uganda. At elevations above 2,000 meters, temperatures are noticeably cooler, with lows around 23°C and daytime highs near 30°C even during warmer periods. The mountains also receive heavier and more frequent rainfall than the plains, making them one of the wettest spots in the country.
The Sudd Wetland’s Local Effect
Central South Sudan is home to the Sudd, one of the largest freshwater wetlands on Earth. The Nile River loses more than half its local flow to evaporation as it passes through this vast swamp, roughly 29 billion cubic meters of water per year out of an average inflow of 49 billion. All that evaporating water shapes the climate immediately around it.
Climate modeling published in Water Resources Research compared today’s conditions to a hypothetical scenario where the Sudd was completely drained. The results showed that without the wetland, relative humidity during the dry season would drop by 30–40%, and local temperatures would rise by 4–6°C. During the wet season, the difference was small because the broader regional rains already saturate the atmosphere. In other words, the Sudd acts as a natural air conditioner for its surroundings, keeping the dry season less brutally hot and more humid than it would otherwise be. This effect is hyper-local, limited to the area around the wetland rather than influencing the wider region.
Dust Storms in the Dry Season
Northern South Sudan experiences haboobs, intense dust storms originally named for the phenomenon in neighboring Sudan. These storms are most common between May and September, typically hitting during the afternoon and evening when thunderstorms are building. A haboob forms when a powerful downdraft inside a thunderstorm slams into the ground and spreads outward, scooping up sand and dust at speeds up to 60 miles per hour. The wall of dust can reach heights of 5,000 feet and extend up to 100 miles wide.
These storms drastically reduce visibility and can last anywhere from minutes to a few hours. They are a regular feature of life in the drier northern regions and the transitional period when dry, dusty ground meets the season’s first thunderstorms.
Flooding and Drought Cycles
South Sudan’s flat terrain and poor drainage make it extremely vulnerable to flooding, particularly along the Nile and its tributaries. In recent years the problem has worsened. A major flood event from 2021 to 2023 was severe enough that water from the Nile River was observed flowing into the Ghazal River system through previously minor channels, something long assumed to be impossible under normal conditions. Hydrological modeling suggests this kind of cross-basin flow only happens during exceptional floods with a return period exceeding 50 years.
Drought is the opposite threat, hitting hardest in the north where rainfall is already marginal. When the rains arrive late or fall short, the planting window shrinks dramatically. Because northern farmers only have a narrow June-to-July window for planting, even a few weeks of delayed rainfall can mean a failed harvest and food shortages lasting months. The combination of recurrent flooding in some areas and drought in others, sometimes in the same year, makes South Sudan one of the most climate-vulnerable countries in East Africa.
How Seasons Shape Daily Life
The rhythm of wet and dry seasons dictates nearly everything in South Sudan. Agriculture is almost entirely rain-fed, so the timing of the rains determines when people plant, when they harvest, and when food is most scarce. The “lean season,” the hungry gap between planting and harvest, falls at different times depending on region. In pastoral areas like Pibor and Greater Kapoeta, farmers plant in June and July and harvest from September through October, leaving the months before harvest as the most food-insecure period.
In the southwest, where rains come earlier, the agricultural calendar is shifted forward by about two months. Planting happens in April and May, and food from the harvest becomes available by August. This means southwestern communities generally face their lean season earlier in the year but also recover sooner. Roads in many parts of the country become impassable during the wet season, cutting off communities from markets and aid. The dry season restores mobility but brings its own challenges: extreme heat, water scarcity, and the dust storms that sweep across the northern plains.