EXPLAINER: La Niña to bring below-average rains in Kenya, what it means

Most of Kenya will receive below-average rainfall between October and December this year, partly due to a weak La Niña that is currently developing.

The rains, which are also expected to start later than usual, could affect millions of households that depend on the short rains season for food production and water security.

The IGAD Climate Prediction and Applications Centre (ICPAC) has projected that much of eastern and northern Kenya will be hotter and drier than usual between October and December, while western counties may receive more favorable rains.

This short rainy season, which supplies up to 70 per cent of annual rainfall in some areas, is crucial for farming and pastoralist communities.

At the 71st Greater Horn of Africa Climate Outlook Forum in Nairobi, ICPAC said there is a 55 per cent chance that central and eastern Kenya will record below-average rainfall, a forecast echoed by the World Meteorological Organization (WMO).

Both agencies link the outlook to a weak La Niña and a developing negative Indian Ocean Dipole (IOD), weather patterns that typically suppress rains in East Africa.

So, what exactly is La Niña, and why does it matter for Kenya?

The World Meteorological Organisation (WMO) defines it as a natural climate phenomenon characterised by cooler-than-average sea surface temperatures in the central and eastern tropical Pacific Ocean.

It is the counterpart of El Niño, which features warmer-than-normal sea surface temperatures in the same region.

Together, these opposing phases form the El Niño–Southern Oscillation (ENSO) cycle, one of the most influential climate patterns in the world.

“Though ENSO is a single climate phenomenon, it has three phases - El Niño, La Niña, and Neutral,” WMO says.

In simple terms, when La Niña occurs, changes in atmospheric circulation alter rainfall patterns across the globe.

Some regions experience heavier-than-usual rainfall and flooding, while others face prolonged dry spells and drought.

For East Africa, La Niña is typically associated with below-average rainfall during the short rains season (October to December).

The Kenya Meteorological Department (KMD) explains that during La Niña years, shifts in wind circulation and pressure systems reduce the amount of moisture transported from the Indian Ocean into East Africa.

This results in suppressed rainfall, delayed onset of the rainy season, and higher-than-average temperatures.

Why it matters for Kenya

Kenya’s reliance on rain-fed agriculture makes the country particularly vulnerable to climate variability.

According to Kenya MET, the October–December short rains account for a significant share of national crop production, especially in central, eastern, and coastal counties.

A delay or reduction in rainfall could therefore lower maize, bean, and vegetable yields at a time when food prices are already under pressure.

“These events can disrupt agriculture, threaten food security, and contribute to humanitarian crises by reducing rainfall and water availability,” reports by the Kenya MET report say.

For pastoralist communities in northern Kenya, depressed rainfall could worsen water and pasture shortages, heightening the risk of livestock losses and conflict over scarce resources.

ICPAC notes that high temperatures expected alongside the weak rains could exacerbate evaporation, reducing soil moisture and further stressing crops and animals.

Urban areas are also likely to feel the effects.

With limited rainfall, hydroelectric power generation may decline, putting pressure on the energy supply.

In addition, water shortages could affect households, businesses, and industries that rely on consistent water flows.

The role of the Indian Ocean Dipole

The negative Indian Ocean Dipole (IOD) is an additional factor likely to worsen conditions.

An IOD occurs when the western Indian Ocean near East Africa becomes cooler than the eastern part near Indonesia.

This imbalance typically suppresses moisture inflow into East Africa while enhancing rains over Australia and Southeast Asia.

Looking ahead

While the forecast paints a challenging picture, both ICPAC and the Kenya Meteorological Department stress that it is not a certainty of drought, but rather an increased probability of below-average rainfall.

Local variations will still occur, with some counties in western Kenya expected to receive near-normal or even above-normal rainfall.

The agencies are urging early preparedness measures, including investment in drought-resistant crops, water harvesting, and efficient irrigation systems.

For pastoralists, livestock vaccination and early planning for grazing patterns are recommended.

As Kenya braces for a weaker-than-normal short rains season, the emerging La Niña serves as another reminder of the country’s vulnerability to global climate systems.