A strengthening El Niño coupled with a positive Indian Ocean Dipole is expected to reshape Kenya's weather in the coming months. /WMOKenya is set for an enhanced October-November-December short rains season with the latest forecast projecting above-average downpour and isolated storms in much of the country.
The Kenya Meteorological Service Authority said the OND 2026 rains are expected to be fairly to well distributed across several parts of the country, with the exception of Turkana and Samburu where distribution is forecast to be poor to fair.
“This season will be marked by prolonged wet spells and occasional isolated storms over several parts of the country,” Kenya Met said.
The outlook shows above-average rainfall in 43 counties, including Baringo, Bomet, Bungoma, Busia, Embu, Garissa, Homa Bay, Isiolo, Kajiado, Kakamega, Kericho, Kiambu, Kilifi, Kirinyaga, Kisii, Kisumu, Kitui, Kwale, Laikipia, Lamu, Machakos, Makueni, Mandera, Meru, Mombasa, Nairobi, Nakuru, Nandi, Narok, Nyamira, Nyandarua, Nyeri, Siaya, Taita-Taveta, Tana River, Tharaka-Nithi, Trans Nzoia, Uasin Gishu and Vihiga, as well as much of West Pokot, Samburu and Marsabit.
Turkana is forecast to receive near-average to above-average rainfall, while some parts of West Pokot, Samburu and Marsabit are also expected to record near-average rainfall with a tendency towards above-average amounts.
The onset will vary considerably across the country.
In western and parts of the Rift Valley, including Nandi, Kakamega, Vihiga, Bungoma, Siaya, Busia, Baringo, Nakuru, Trans Nzoia, Uasin Gishu, Elgeyo-Marakwet, West Pokot, Kisii, Nyamira, Kericho, Bomet, Kisumu, Homa Bay, Migori and Narok, the rains are expected to continue from September into January.
In Nyandarua, Laikipia, Nyeri, Kirinyaga, Murang’a, Kiambu, Meru, Embu, Tharaka-Nithi and Nairobi, onset is expected between the second and third weeks of October, with the rains continuing into January.
Machakos, Kitui, Makueni, Kajiado, Taita-Taveta and inland parts of Tana River are expected to receive the rains from the third to fourth week of October, also extending into January.
Along the Coast, including Mombasa, Kwale, Lamu, Kilifi and the Tana Delta, onset is expected between the second and third weeks of October before cessation between the first and second weeks of December.
Turkana and Samburu are expected to experience onset in the third to fourth week of October, with the rains ending in the first week of December.
Marsabit, Mandera, Wajir, Garissa and Isiolo are forecast to receive the rains from the second to third week of October, with cessation expected in the first or second week of December.
The enhanced rainfall outlook comes as the 2026 El Niño event continues to intensify over the central-eastern equatorial Pacific.
The temperature of the Pacific Ocean used to measure El Niño rose from 1.51°C above normal between May and July, to 2.03°C in July, and then to 2.7°C by the week of August 12.
The readings, the weatherman said, indicate that El Niño is strengthening further and evolving towards a very strong event.
The Indian Ocean Dipole (IOD), another key driver of OND rainfall, is currently neutral but is expected to strengthen and cross the positive threshold from September, although uncertainty remains over the timing and strength of the shift.
As of August 23, the weekly IOD index stood at +0.17°C, below the +0.4°C threshold required for a positive IOD event.
Kenya Met forecasts a peak seasonal IOD value of +0.7.
It says the OND season is particularly important in eastern and parts of southeastern Kenya, where it contributes more than 40 per cent of annual rainfall in counties including Garissa, Wajir, Mandera, Marsabit, Isiolo, Meru, Tharaka-Nithi, Makueni, Kitui, Taita-Taveta and Machakos, as well as parts of Kajiado and Tana River.
The enhanced rainfall is also expected to reduce drought risk, with Kenya Met forecasting a low probability of mild, moderate or severe drought over most parts of the country, although Turkana faces a 15 to 20 per cent chance of a mild drought event.
Kenya Met says the outlook will be updated through weekly and monthly forecasts as the season approaches.
