The Kenya Meteorological Department (KMD) has issued a statement on the onset of the March-April-May (MAM) seasonal rainfall. In a statement on March 17, Kenya Met Director, Dr. David Gikungu, explained that the onset of the March-April-May (MAM) “Long Rains” Season is specifically defined as the first day of the wet season when two key conditions are met.
First, a wet spell must occur, characterized by accumulated rainfall of at least 20 mm over three consecutive days.
Following this wet spell, there should be no dry spell (a period with little to no rainfall) of at least 7 days within the next 21 days.
“For the Northern part of the country, the accumulated rainfall should be at least 10 mm over three consecutive days,” Gikungu said.
He said the rains recorded during the week of 10 to 16 March 2025 marked the onset of the MAM 2025 season.
This is majorly for the Highlands West of the Rift Valley, Lake Victoria Basin, Rift Valley, Nairobi and isolated areas over the Highlands East of the Rift Valley, the Southeastern lowlands and parts of Isiolo County.
Compared to the week of 3 to 9 March 2025, there was a noticeable increase in rainfall amounts, especially in the Southeastern lowlands and parts of Northeastern regions.
Long Rains Dates for Other Parts
Gikungu said the remaining parts of the Highlands East of the Rift Valley and Southeastern lowlands are expected to have their onset this week.
The onset for the Northeastern region is also expected this week between 18th and 24th March and next week from 25th to 31st March.
However, this is likely to be followed by dry spells.
Also Read: Kenya Met Announces Temporary Break in Rains, Predicts Return Date
The Northwestern parts of Kenya and coastal regions are expected to receive occasional rainfall during the remaining part of March 2025.
He however clarified that this may not meet the onset criteria.
“The peak of the season in the coastal region is expected to occur in May. The onset is likely to occur in April in both regions,” Gikungu said.
Also Read: Kenya Met Lists Regions Set for Heavy Rains Starting Sunday
Rainfall to Continue- Kenya Met
In the forecast for this week, rainfall is expected to continue over several parts of the country.
Isolated heavy rainfall events are likely to occur in some areas, particularly over the Highlands East and West of the Rift Valley including Nairobi County, the Lake Victoria Basin, the Rift Valley, the Southeastern lowlands, and Northeastern Kenya.
Residents in these regions are advised to remain alert of potentially heavy downpours and take necessary precautions to ensure safety.
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