Nairobians brave heavy rainfall early in the morning along various parts of Nairobi CBD on April 29, 2026. / Leah MukangaiThe weatherman is yet to declare the onset of the El Niño rains, but has warned light showers will hit 36 counties on Saturday and continue next week.
Jemimah Gacheru, a principal meteorologist at the Kenya Meteorological Service Authority (KMSA) advised Kenyans to follow forecasts from the regional county offices of the Met service.
She noted light rains and showers are expected in 36 counties from Saturday, giving farmers a possible first sign of the coming October-December rainy season.
However, the Met service did not declare this as the onset of the season.
The department’s five-day forecast, valid from Thursday to Monday, shows rain spreading to Mombasa, Kwale, Kilifi, Tana River, Lamu, Taita Taveta, Garissa, Wajir, Mandera, Marsabit, Isiolo, Meru, Tharaka Nithi and Embu counties.
Others are Kitui, Machakos, Makueni, Nyandarua, Nyeri, Kirinyaga, Murang’a, Kiambu, Samburu, Elgeyo Marakwet, Baringo, Laikipia, Kajiado, Vihiga, Siaya, Kisumu, Homa Bay and Nyamira counties.
Nairobi is also expected to receive light rain on Saturday, with moderate showers in the afternoon.
“This forecast should be used in conjunction with the daily (24-hour) forecast issued by this department. County-specific forecasts are available from the offices of the respective county Directors of Meteorological Services,” Gacheru said.
For Kenya Met, the onset of a rainy season is not simply the first day it rains.
At least 20mm of rain must fall within three consecutive days, and there must not be a dry spell lasting more than seven days afterwards.
Not all farmers should expect rain this weekend.
Turkana, West Pokot, Trans Nzoia, Uasin Gishu, Nandi and Narok are forecast to remain generally dry on both Saturday and Sunday.
Some of these counties are expected to start receiving showers from Sunday or later in the forecast period, but the Met forecast does not show rain for Saturday in these areas.
The forecast also shows some counties that remain dry on Saturday could receive rain on Sunday. These include Nakuru, Kericho, Bomet, Kakamega, Bungoma, Busia, Migori and Kisii.
Many farmers are waiting for heavy rains during the October-December season, especially after warnings of a strong El Niño.
The World Meteorological Organization said in September that El Niño is firmly established and is expected to become very strong towards the end of the year. It also said there is nearly a 100 per cent chance the event will continue through February 2027.
The WMO and regional climate outlooks have also indicated a higher chance of wetter-than-normal conditions in the Greater Horn of Africa during the last quarter of 2026.
The October-December forecast released during the 13th National Climate Outlook Forum in Nairobi, in August indicated the rains would begin in early October across most parts of the country and continue until January.
Charles Mugah, deputy director at the Kenya Meteorological Department, said this year’s rainy season is being driven by the Indian Ocean Dipole (IOD) and El Niño.
He said the IOD refers to the difference in sea surface temperatures between the western and eastern Indian Ocean.
When waters on the western side, near Kenya, become warmer than those in the east, a positive IOD develops, bringing heavier rainfall to Kenya and neighbouring countries.
Mugah said the IOD is currently neutral but is expected to turn positive from September, reaching levels close to those recorded in 2015, when Kenya experienced widespread flooding.
Mugah said rainfall had already begun in 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. It is expected to continue and intensify until January.
He predicted the rains would begin between the second and third weeks of October in Nyandarua, Laikipia, Nyeri, Kirinyaga, Murang’a, Kiambu, Meru, Embu, Tharaka Nithi and Nairobi and continue until January.
In Mombasa, Kwale, Lamu, Kilifi, Tana Delta, Marsabit, Mandera, Wajir, Garissa and Isiolo, the rains are expected to begin between the second and third weeks of October and end between the first and second weeks of December.
Machakos, Kitui, Makueni, Kajiado, Taita Taveta and inland parts of Tana River county are expected to receive rainfall from the third to the fourth week of October, with the season continuing into January.
Turkana and parts of West Pokot, Samburu and Marsabit may receive less rainfall than the rest of the country.
Mugah said there is a 15 to 20 per cent chance of a mild drought in Turkana, even as much of Kenya experiences above-normal rainfall.
“Updates on the onset, distribution and cessation of rainfall will be provided regularly through weekly and monthly forecasts as the season approaches. These updates will offer detailed insights into changes in rainfall patterns to keep stakeholders informed and support timely decision-making,” Mugah said.
Edward Muriuki, acting director at the Kenya Meteorological Service Authority, said the forecast would only be useful if people acted on it early.
“Climate information must be understandable, relevant and actionable,” Muriuki said.
Instant analysis
The expected El Niño season is moving closer, but the first showers should not be mistaken for its official onset. With rain forecast across 36 counties, the immediate challenge is for farmers and authorities to act on increasingly localised forecasts rather than wait for heavier rains. The contrasting dry conditions in several counties also underline why preparedness must be guided by county-specific information, not broad national expectations alone.
