Experts Warn Farmers, Kenyans Over Abnormal Rains as El Niño, IOD Raise Flood Risk

Experts have warned Kenyans to prepare for an unusually early and potentially intense rainy season, with new forecasts indicating that pre-seasonal rains could begin in parts of the country as early as September.

Weather expert Maithya wa Vilivū said the latest August multi-model forecasts point to an early onset of the October-December (OND) rainy season, particularly in North Eastern Kenya and the coastal strip.

According to Maithya, the rains are expected to initially affect Somalia, Eastern Ethiopia, and parts of Kenya before intensifying and spreading to other parts of the country from early October.

“One of the key parameters that we use to know when the OND rainy season will begin is the consistent emergence of rain bands in Eastern Ethiopia, Somaliland, and Somalia,” Maithya said.

He explained that the emergence of the rain bands normally signals the southward movement of the Inter-Tropical Convergence Zone (ITCZ) from the Sahel and Ethiopian highlands towards Equatorial Africa, including Kenya.

The latest forecasts project above-average rainfall in September in the affected areas, with some locations potentially recording up to 20mm above the long-term average.

“These rains are expected to intensify quickly and spread out to other parts of Kenya from early October and continue to drench the lands all the way to January 2027,” Maithya said.

The forecast comes against the backdrop of growing international warnings over a strengthening El Niño weather pattern and the development of a positive Indian Ocean Dipole (IOD), two climate patterns that could influence rainfall across East Africa in the coming months.

The World Meteorological Organisation (WMO), in its Global Seasonal Climate Update released on July 31, warned that El Niño was strengthening and could become a strong event between August and October, increasing the likelihood of major shifts in global rainfall patterns.

For Kenya and the wider Greater Horn of Africa, the WMO outlook pointed to wetter-than-normal conditions between August and October, raising the possibility of heavier rainfall, localised flooding, and other weather-related disruptions.

The WMO has also warned that El Niño will not be acting alone. A positive IOD, characterised by warmer-than-normal waters in the western Indian Ocean near East Africa and cooler waters near Indonesia, could reinforce the flow of moisture towards Kenya and other countries in the region.

Maithya said the combination of the prevailing climate conditions could make the expected rains particularly concerning, although the exact timing and intensity will only become clearer as short-range and sub-seasonal forecasts are released in the coming weeks.

The warning comes as the Kenya Meteorological Service has already been forecasting showers and thunderstorms across several parts of the country.

Its July 28 to August 3 outlook indicated that afternoon showers and thunderstorms could occur in counties including Nairobi, Kisumu, Kakamega, Bungoma, Uasin Gishu, Nakuru, and Turkana, while night showers were expected in several western counties.