NAIROBI, Kenya- Kenya is set for an unusually wet October-to-December period, with the Kenya Meteorological Service Authority (KMSA) forecasting above-average rainfall across large parts of the country during the 2026 short-rains season.
In a technical statement issued on Wednesday, August 26, KMSA said enhanced rainfall is expected in more than 40 counties, raising the prospect of prolonged wet spells and isolated storms during the season.
The forecast comes as a strong El Niño event continues to intensify over the central and eastern equatorial Pacific Ocean.
KMSA said the Niño 3.4 index reached a seasonal mean of 1.51°C between May and July, while the July monthly value rose to 2.03°C.
The weekly index centred on August 12 reached 2.7°C, pointing to what the authority described as a very strong El Niño event.
The Indian Ocean Dipole (IOD), another important driver of rainfall in East Africa, remains neutral but is expected to strengthen.
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.
KMSA expects the index to cross the threshold from September, although uncertainty remains over the timing and strength of the shift.
A positive IOD occurring alongside El Niño can enhance rainfall over parts of East Africa.
KMSA expects above-average rainfall in counties including Nairobi, Murang’a, Kiambu, Nyeri, Nyandarua, Kirinyaga, Nakuru, Bomet, Kericho, Kisii, Nyamira, Kisumu, Homa Bay, Siaya, Kakamega, Bungoma, Busia, Machakos, Kitui, Makueni, Meru, Embu, Garissa, Wajir, Mandera, Marsabit and Isiolo.
The outlook also covers much of the Coast, including Mombasa, Kilifi, Kwale and Lamu, as well as parts of Kajiado, Narok, Samburu, West Pokot and Tana River.
For Nairobi, Kiambu, Murang’a, Nyeri, Nyandarua, Kirinyaga, Laikipia, Meru, Embu and Tharaka-Nithi, the rains are expected to begin between the second and third week of October and continue into January.
In western Kenya, including Nandi, Kakamega, Vihiga, Bungoma, Siaya, Busia, Kisumu, Homa Bay, Migori, Kisii, Nyamira, Kericho and Bomet, rainfall is expected to continue from September and extend into January.
The Coast is expected to receive the rains from the second to third week of October, with the season likely to end between the first and second week of December.
KMSA said the rainfall is expected to be fairly to well distributed over most parts of the country. However, Turkana and Samburu could experience poor to fair distribution.
Despite the wetter outlook, the authority said the probability of drought is low across most of Kenya. Turkana has a 15 to 20 per cent chance of experiencing a mild drought.
The wetter conditions could bring benefits to agriculture, water resources and livestock, but may also increase the risk of flooding, waterlogging, crop losses and storm-related disruption in vulnerable areas.
KMSA also forecasts warmer-than-average temperatures during the season, particularly in parts of the Coast and northeastern Kenya.
The authority urged Kenyans and other stakeholders to continue monitoring subsequent forecasts, noting that rainfall patterns can change because of shorter-term climate drivers such as the Madden-Julian Oscillation and tropical cyclones over the southwest Indian Ocean.
KMSA said the outlook should be used alongside its daily, five-day, seven-day, monthly and special forecasts as the rainy season approaches.
