The Kenya Meteorological Department (Kenya Met) has released a new update on the onset of the March–April–May (MAM) 2026 long rains, confirming that several regions have already met the official rainfall threshold, while others are expected to experience delayed onset.
In a statement issued on Tuesday, February 24, the department reiterated that the March to May season remains Kenya’s primary rainfall period, particularly across most parts of the country and the wider equatorial East Africa region.
“The March to May period is the major rainfall season (Long Rains) over most parts of Kenya and much of equatorial East Africa. The highest seasonal rainfall amounts — greater than 300mm — are normally received over the Lake Victoria Basin, the Highlands West of the Rift Valley, the Central and South Rift Valley, the Highlands East of the Rift Valley including Nairobi County, and the Coastal Strip,” the statement read.
Regions that have met onset criteria
According to the updated outlook, western, central, and highland regions — including Nairobi — officially realized the onset of the long rains from mid-February.
Areas in the Highlands West of the Rift Valley, Lake Victoria Basin, Central and South Rift Valley, and the Highlands East of the Rift Valley have already met the scientific benchmark for rainfall onset.
The Southeastern Lowlands — including Kajiado, Kitui, Makueni, Machakos, Tana River, and Taita Taveta — met the onset criteria during the fourth week of February.
Kenya Met clarified that rainfall onset is scientifically defined as the receipt of at least 20 millimetres of rainfall within three consecutive days, followed by no dry spell exceeding seven days.
Delay expected in some regions
However, not all regions have officially entered the rainy season.
For North Coast counties such as Lamu, Malindi, coastal parts of Tana River, and Kilifi, onset is projected between late March and early April despite intermittent rainfall already experienced.
Similarly, northwestern counties including Turkana and Samburu, as well as northeastern counties — Wajir, Isiolo, Garissa, Mandera, and Marsabit — are expected to realize onset between the first and second week of April.
Possible fluctuations ahead
While the early rains have been encouraging in several areas, Kenya Met cautioned that rainfall performance may fluctuate in the coming weeks.
The department cited the influence of the Madden–Julian Oscillation (MJO), a large-scale atmospheric system that affects tropical rainfall patterns.
“Indications suggest that the Madden–Julian Oscillation (MJO) is likely to transition to less favourable phases from mid-March, which may result in a reduction in rainfall amounts and an increased likelihood of dry spells, as the convective environment becomes suppressed over some regions,” the statement noted.
Kenya Met attributed the early seasonal rainfall to favourable mesoscale and large-scale atmospheric systems, including enhanced convective activity linked to the MJO. These systems are expected to temporarily boost moisture convergence and rainfall amounts across several parts of the country from late February into early March.
Heavy rains forecast in seven regions
Separately, the department warned of heavy rainfall in seven regions during the week running from February 24 to March 2, 2026.
The Central Highlands, Lake Victoria Basin, Rift Valley, and South-eastern Lowlands are expected to receive significant downpours. The Coast, Western, and North-western Kenya regions are also likely to experience heavy rains during the same period.
Residents in affected areas have been urged to remain alert for possible localized flooding, especially in low-lying and poorly drained zones.
Temperature extremes expected
In addition to rainfall, Kenya Met projected cold nights with minimum temperatures below 10°C in parts of the Central Highlands, Central Rift Valley, Western Kenya, and areas near Mt. Kilimanjaro.
Conversely, hot daytime conditions with maximum temperatures exceeding 30°C are expected across the Coast, South-eastern Lowlands, and much of North-eastern and North-western Kenya.
Advisory to farmers and stakeholders
The department emphasized the importance of relying on continuous forecasts and expert guidance throughout the season.
“This outlook should be used together with the 24-hour, 5-day, 7-day, monthly and special forecasts, as well as regular updates and advisories issued by this Department, in addition to the Weekly and Monthly County forecasts developed and disseminated by the County Meteorological Offices. Farmers are advised to consult Agricultural Extension Officers for further guidance and decision-making,” the statement concluded.
With the long rains season now underway in several parts of the country, attention will turn to rainfall consistency and distribution — key factors that will determine agricultural output, water availability, and overall economic activity in the coming months.
