Kenya’s sudden August downpour: What caused it and why it turned deadly

Kenya was caught off guard by a wave of deadly and intense rains between August 17 and 19, 2025, a sudden weather event that experts now say was triggered by rare global weather systems.

The Kenya Meteorological Department has linked the abrupt and severe downpour to two powerful phenomena that, when combined, created the perfect conditions for excessive rainfall, leading to localised flooding and disruptions across several parts of the country.

At the centre of this unusual event was the Madden–Julian Oscillation (MJO), a tropical system that moves around the world in different phases.

During the three-day period, this system was in its second and third phases, positioned over the Indian Ocean — a location known to trigger rainfall in East Africa.

“This system is classified into eight phases and brings rainfall over the country when it moves over the Indian Ocean (phases 2 and 3). Currently, the MJO is in phase 3 and is expected to remain in that phase for the next couple of days,” the department stated.

The second key factor that intensified the rains was a shift in the pressure gradient caused by a cooler-than-normal Atlantic Ocean. This shift pushed the rain-bearing system farther east than usual, directly over Kenya.

“When the Atlantic Ocean is cooler than the Indian Ocean, the pressure gradient between these two oceans pulls the rain causing system farther eastwards to the Central parts, including Nairob,i leading to enhanced rainfall over these areas during the June to August season,” Acting Director of Kenya Meteorological Services, Edward M Muriuki explained.

These two weather systems, acting together, created stronger cloud activity and more intense rain than typically seen during this period.

According to the meteorological department, the combination of the MJO and pressure changes created “a perfect setup for enhanced convection and heavier rainfall across the country.”

Although the rains only lasted a few days, the impact was significant.

In some areas, the downpour caused floods that disrupted transport, daily movement, and business activities.

Roads were cut off, homes were affected, and emergency services were stretched thin in places where flooding struck hardest.

The department has since confirmed that the rare weather patterns are easing, and conditions are beginning to stabilise.

Still, they are monitoring weather activity closely to offer timely forecasts, especially as the country prepares for the upcoming short rains season.

Kenyans are being urged to remain cautious and stay informed through official forecasts to avoid further danger.