Forecasters trace the three-day burst of rain and chill to the Madden–Julian Oscillation and a cool patch of the Atlantic Ocean.”,
Kenya’s weathermen have pinned last week’s chilly skies and pounding rain on two powerful but normally separate climate drivers that aligned over East Africa.
Between August 17 and August 19, swathes of the country received well above the season’s average rainfall, flooding low-lying neighbourhoods even as farmers welcomed the extra moisture.
In a technical brief released on August 26, the Kenya Meteorological Department (KMD) said the downpour was caused by the combined influence of the Madden–Julian Oscillation (MJO) over the Indian Ocean and unusually cool sea-surface temperatures in the tropical Atlantic.
The MJO, a massive pulse of clouds and thunderstorms that circles the globe every 30 to 60 days, was passing through Phases 2 and 3 when the rains hit.
Those stages sit squarely over the western and central Indian Ocean and tend to pump warm, humid air toward East Africa.
While the MJO was enhancing convection, a cooler-than-normal Atlantic created a pressure imbalance that pushed the rain belt farther east than usual,” the department noted.
The opposing pressures funnelled deep moisture into Kenya, turning what is normally a dry stretch of August into a sodden three-day spell.
KMD had warned of the threat a day earlier. In an advisory posted on X (formerly Twitter) on August 16, the agency told residents in 30 counties to brace for more than 20 millimetres of rain in 24 hours, strong southerly winds topping 25 knots (12.9 m/s) and possible flash floods.
The heaviest showers were expected over the Lake Victoria Basin, the Rift Valley and the highlands on both sides of the valley.\n\nThe forecast proved accurate.
Rivers burst their banks in parts of Homa Bay and Busia counties, while traffic ground to a halt on several rural roads.
At the same time, tea and maize growers in Kericho and Uasin Gishu said the moisture would help crops planted earlier in the month.\n\nBy Wednesday, August 20, the system had started to weaken, and KMD expects normal cool-dry conditions to resume over much of the country.
Even so, the agency is keeping a close eye on the larger climate picture as forecasters compile the outlook for the October to December short-rains season.
“These conditions have since eased, but the Kenya Meteorological Department continues to monitor evolving patterns closely,” the update stressed.
Residents have been urged to remain alert, especially in flood-prone zones, until soils dry out and river levels recede.
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