East Africa’s climate is shaped primarily by its position straddling the equator, which gives most of the region two rainy seasons and two dry seasons each year rather than the four-season pattern familiar in temperate countries. But “East Africa” covers enormous geographic variety, from sea-level coastlines to 5,895-meter volcanic peaks, from lush lakeside basins to near-desert plateaus receiving just 250 mm of rain a year. The result is not one climate but a patchwork of climates, all driven by a few powerful forces.
Why East Africa Has Two Rainy Seasons
The single biggest influence on East African weather is the Intertropical Convergence Zone, or ITCZ, a belt of clouds, showers, and thunderstorms that encircles the globe near the equator. The ITCZ follows the sun’s position: it shifts north during the Northern Hemisphere summer and south during the Northern Hemisphere winter. Because the sun crosses the equator twice a year, in March and September, equatorial East Africa gets two distinct wet seasons.
The first, called the “long rains,” runs from roughly March through May. These rains are heavier and more sustained. The second, the “short rains,” falls between October and December and tends to be lighter and briefer. Between these wet periods come two dry seasons, centered on the months when the sun is farthest from the equator (around July and January). In some areas, including parts of Kenya and Uganda, recent years have brought earlier rainfall in January and February, effectively stretching the wet season beyond its traditional boundaries.
Farther from the equator, the two wet seasons gradually merge into one. Northern Ethiopia and parts of South Sudan, for example, experience a more monsoon-like pattern with a single prolonged rainy season and a single long dry spell.
The Ethiopian Highlands: A Different Pattern
Ethiopia’s highland plateau, much of which sits above 2,000 meters, follows its own seasonal calendar. The main rainy season, called Kiremt, runs roughly from June through September and supplies the bulk of the year’s moisture. It is followed by Bega, the dry season spanning October through January, which also serves as the main harvest period. A lighter rainy season, Belg, arrives between February and May in some parts of the highlands.
Temperatures on the plateau are notably cooler than lowland East Africa. Highland areas can experience frost, particularly during extreme minimum temperature events in the dry season. This altitude-driven coolness is why Addis Ababa, at around 2,400 meters, has average temperatures closer to a mild European spring than to what most people picture for equatorial Africa.
Coastal Heat and Humidity
Along the Indian Ocean coast, from southern Somalia through Kenya, Tanzania, and into Mozambique, the climate is hot and humid year-round. Average temperatures exceed 27 °C (about 80 °F) in most coastal areas, and relative humidity stays high regardless of season. The monsoon winds that blow across the Indian Ocean moderate extremes slightly but keep moisture levels persistently elevated. Cities like Mombasa and Dar es Salaam feel noticeably more oppressive than inland cities at similar latitudes simply because of this coastal moisture.
Arid Lowlands and Semi-Desert
Not all of East Africa is green. The inland plateaus of northern Kenya, much of Somalia, and Djibouti receive very little rainfall. On the driest plateaus, average annual precipitation drops to around 250 mm (about 10 inches), comparable to parts of the American Southwest. Temperatures are high, vegetation is sparse, and communities depend heavily on pastoralism and seasonal water sources. These semi-arid zones are the most vulnerable when rains fail, which happens with increasing regularity.
How the Indian Ocean Drives Extreme Years
Year-to-year swings in East African rainfall, especially during the short rains, are strongly influenced by two ocean-atmosphere patterns: the Indian Ocean Dipole (IOD) and El Niño-Southern Oscillation (ENSO).
The IOD describes temperature differences between the western and eastern Indian Ocean. During a “positive” IOD event, the western Indian Ocean warms relative to the east, pumping extra moisture toward the East African coast. The result is heavier-than-normal short rains. The 2019 positive IOD, for instance, produced one of the wettest short-rain seasons in recent decades, triggering widespread flooding. Negative IOD events do the opposite, suppressing rainfall and raising the risk of drought. El Niño events can reinforce these effects, pushing already-wet seasons into flood territory or deepening dry spells.
Climate projections suggest the IOD’s influence on the Horn of Africa will strengthen under global warming. That means both extremes, unusually heavy rains and severe droughts, are expected to become more frequent and more intense.
Lake Victoria’s Nighttime Storms
Lake Victoria, the largest lake in Africa, creates its own weather system. During the day, air rises over the warm land surrounding the lake and sinks over the cooler water, suppressing rain over the lake itself. At night, the pattern reverses. Cool air flows downslope from the eastern highlands toward the lake, converging over the water and triggering intense thunderstorms. These storms peak between midnight and early morning, with the heaviest rainfall displaced toward the lake’s western and southwestern shores because the eastern downslope winds are so dominant they push the storm activity in that direction.
This nocturnal storm cycle is not just a meteorological curiosity. It is deadly. An estimated 3,000 to 5,000 people die over the lake from storm-related winds, waves, and lightning, largely because most fishing on Lake Victoria happens at night, putting small boats directly in the path of these storms. The surrounding catchment also receives a secondary rainfall peak in the early morning hours as storms initiated over the lake drift onshore.
Climate Zones on a Single Mountain
East Africa’s tall volcanic peaks compress multiple climate zones into a few vertical kilometers, offering a vivid demonstration of how altitude reshapes climate. Mount Kilimanjaro, the continent’s highest point at 5,895 meters, passes through five distinct zones on the way up:
- Bushland and savanna (800 to 1,800 m): hot, dry grassland on the northern and western slopes, with the southern and eastern slopes largely converted to farmland.
- Rainforest (1,800 to 2,800 m): dense, wet forest that intercepts the most rainfall on the mountain.
- Heather and moorland (2,800 to 4,000 m): cooler, misty terrain with shrubby vegetation.
- Alpine desert (4,000 to 5,000 m): barren, cold, and dry, with wide daily temperature swings.
- Arctic summit zone (above 5,000 m): glacial ice and rock, though the glaciers have been retreating rapidly for decades.
Mount Kenya follows a similar pattern. These altitude-driven climate gradients mean that a farmer at the base of the mountain and a climber near the summit, separated by only a few dozen horizontal kilometers, experience completely different worlds.
Drought as a Recurring Crisis
East Africa is one of the most drought-vulnerable regions on Earth. The Horn of Africa, encompassing Somalia, eastern Ethiopia, and eastern Kenya, has experienced repeated multi-season rainfall failures in recent years. The most recent severe drought, building since September 2025, has damaged crops, killed livestock, and driven cereal prices to record highs across the region. By early 2026, roughly 4.6 million people were affected in Somalia alone, with over 135,000 displaced. Emergency-level food insecurity was reported across Somalia, southeastern Ethiopia, and eastern Kenya, accompanied by rising acute malnutrition in children.
These droughts are not isolated events. The region experienced a historic five-consecutive-season drought from late 2020 through 2022, and shorter droughts have struck repeatedly over the past two decades. With negative IOD events projected to become more extreme under climate change, the frequency and severity of these dry spells is expected to increase, placing ever-greater pressure on communities that depend on rain-fed agriculture and pastoralism.