El Niño's Long Reach: Drought and Flood from the Pacific to the Horn

In early 2016, Hasna, a pastoralist in Ethiopia’s Somali Region, watched the last of her goats collapse onto the cracked, sun-blasted soil. The seasonal rains that should have carpeted the rangelands in fresh grass never came. Across southeastern Ethiopia, the parched earth held nothing but dust and despair. In some districts, pastoralists lost 40 to 60 percent of their livestock—the animals that were their savings, their food, their identity. The drought, the worst Ethiopia had seen in decades, pushed over 10 million people into acute food insecurity. Hasna’s story was one of tens of thousands, but it wasn’t a story of simple bad luck. It was the frontline of a planetary event.

Almost exactly the same season, Josiah, a smallholder farmer in Kenya’s Tana River County, stood in waist-deep water amid what used to be his maize field. Torrential rains had been pounding southern Kenya since October 2015. The Tana River swelled, burst its banks, and swallowed villages, roads, and crops. By December, flooding had displaced roughly a quarter of a million Kenyans, destroyed food stores, and sparked cholera outbreaks. Josiah lost his harvest, his income, and his confidence in the seasons he thought he knew.

Two neighbors. Two opposite disasters. Both unfolding during the same months. Both tied to the same cause: a vast, warm pool of water in the distant equatorial Pacific. As strange as it sounds, the very ocean that touches neither Ethiopia nor Kenya had reached across half the planet to twist their fates in opposite directions. How is that possible?

If you’ve never lived in a drought-prone region, it’s tempting to think of weather as something local—formed by nearby hills, a coastline, or the memory of last year’s rains. Even within East Africa, the instinct is to search for an explanation in the sky above: a delayed monsoon, a weak rainy season, an unlucky streak. Surely, the thinking goes, a drought in Ethiopia and a flood in Kenya are just two separate, regional misfortunes.

This intuition is not foolish, but it is incomplete. The atmosphere is not a patchwork of independent weather machines. It is a single, restless ocean of air, and what happens in one part of it can—and does—reshape the lives of people thousands of kilometers away. To see Hasna’s goats and Josiah’s maize as connected, we need a new lens: the teleconnection.

A teleconnection is a causal chain linking climate anomalies in remote regions through the atmosphere’s global circulation. It’s not mere correlation. It’s a physical pathway, like a row of dominoes stretching from the Pacific warm pool to the Horn of Africa. To follow that chain, we must first meet the engine that normally drives tropical weather: the Walker circulation.

Picture the equatorial Pacific as a basin of wind. Under typical conditions, strong easterly trade winds push sun-warmed surface water westward, piling it up near Indonesia and Papua New Guinea. There, the water is a bathtub-warm 29°C or more, and it feeds towering thunderstorms that act like planetary chimneys. Warm, moist air rises, travels east high up, and then sinks over the cooler waters near South America—completing a vast horizontal loop. This is the Walker cell, and it’s what keeps the eastern Pacific relatively dry and the western Pacific drenched.

Now imagine the thermostat breaks. For reasons scientists are still refining, every two to seven years the easterly winds weaken or even reverse. The warm surface water sloshes eastward toward the central and eastern Pacific, its convection migrating with it. The great chimney of rising air shifts its position by thousands of kilometers. This is El Niño, and it knocks the Walker circulation into a wobble that reverberates around the planet.

Here’s where the detective work gets fascinating. As the massive cluster of thunderstorms relocates over the central Pacific, it generates atmospheric waves—disturbances in the upper-level flow—that alter the paths of moisture and airmasses far downstream. One of these alterations is like a kink in a garden hose: it deflects the moisture that might normally swing north into Ethiopia during the October–December short rains, and instead funnels it southward across Kenya and Tanzania. The result is a north-south see-saw of rainfall: dry conditions in the northern sector of East Africa, and surplus rain in the southern sector.

Draw that picture in your mind, as if looking at a rainfall anomaly map: the Somali Region of Ethiopia and northern Somalia shaded in harsh reds and oranges (rainfall far below normal), while Kenya and southern Somalia are swamped in deep blues (rainfall far above normal). The same Pacific warming; two utterly inverted outcomes.

Hasna and Josiah were living through that map. The 2015–16 El Niño ranked among the three strongest events on record. In Gode and Afder zones of Ethiopia’s Somali Region, the failure of both the spring and the crucial autumn rains meant that herders like Hasna saw their goats, cattle, and camels weaken and die at catastrophic rates. Even experienced pastoralists, who normally manage aridity by splitting herds, migrating over long distances, and tapping clan networks for support, found their traditional buffers exhausted. The drought wasn’t just long; it was locked into a global atmospheric pattern that offered no local escape.

Across the border in southern Kenya, Josiah’s plight was the mirror image. The Tana River basin received relentless rain from October into December 2015. Floodwaters inundated croplands, washed away bridges, and forced families onto higher ground in makeshift camps. Yet that torrential rain, as destructive as it was, also created an unexpected boon for some. In the arid rangelands of northern Kenya, where pastoralists had been struggling with prior dryness, the heavy rains regenerated pasture and refilled pans—temporarily. The same global event could be a thief to one community and a fleeting gift to another. Such is the complex, uneven face of teleconnection.

It’s critical not to paint the whole region with one brush. While eastern Ethiopia endured severe drought, the cool, moist highlands of western Ethiopia recorded near-normal rains that year, because their main rainy season peaks earlier in summer, largely outside the window of El Niño’s strongest influence. This patchwork of impacts—drought here, flood there, normal elsewhere—is exactly what makes teleconnections so hard to internalize and so vital to understand.

Now step back and think: if you were an aid coordinator or a national forecaster in 2015, knowing only that a powerful El Niño was brewing, what would you predict? History offers clues. In the strong El Niño of 1997–98, eastern Africa witnessed a remarkably similar north-south split: drought in Ethiopia, devastating floods in Kenya and Somalia. The same happened in 1982–83. This recurrence isn’t superstition; it’s the signature of a physical mechanism that links Pacific temperatures to the short-rain season in East Africa.

So when another El Niño stirs—as one did in 2023–24—a different kind of preparedness becomes possible. Instead of treating East Africa as a uniform climate zone, agencies can issue heterogeneous early warnings: drought alerts for Ethiopia’s pastoral lowlands, food-security contingency plans for Somaliland, flood watches for the Tana River basin and parts of southern Somalia, and public health preparations for waterborne disease in flood-affected areas. Some communities will need stockpiled food and water, others will need prepositioned shelter and chlorine tablets—all because of what a warm ocean in the Pacific is about to do to the air above them.

The mental move here is to replace the default assumption—that weather is local and coincidental—with a causal map that stretches across basins. Teleconnections don’t just describe the atmosphere; they re-draw the map of risk, creating a landscape where two pastoralist families living a few hundred kilometers apart can face opposite, life-altering extremes from the very same global event. Understanding that connection doesn’t solve the crises, but it does make them less surprising, and surprise is often the deadliest ingredient of all.

Choose a recent El Niño event, such as the 2023–24 episode, and find reliable rainfall anomaly data or reports for Ethiopia and Kenya (a good starting point is the FEWS NET website or the Kenya Meteorological Department’s seasonal assessments). Then imagine you are an aid worker based in Nairobi, writing a brief memo to your organization’s headquarters. Explain, in your own words, why one region urgently needs drought relief while another needs flood assistance in the same season. Be specific about which areas need which response, and note any uncertainties you cannot resolve from the data alone. Your memo should make clear that both requests are not contradictory but are both consequences of the same planetary-scale climate mechanism.