The Kenya Meteorological Department (KMD) has officially announced the onset of the March-April-May (MAM) “Long Rains” season, warning that heavy showers will soon affect several regions across the country.

In a statement issued on March 17, 2025, Kenya Met Director Dr. David Gikungu outlined the specific conditions that define the onset of the rainy season.

According to Gikungu, the season begins when two primary criteria are met: a wet spell with a cumulative rainfall of at least 20 mm over three consecutive days, followed by no dry spell lasting seven days or more within the subsequent 21 days.

For regions in the Northern part of Kenya, the threshold for rainfall accumulation is set lower at 10 mm over three consecutive days.

Areas Already Experiencing Heavy Showers

Dr. Gikungu confirmed that the rainfall recorded between March 10 and March 16 marked the official onset of the MAM 2025 season in several areas. These include:

• Highlands West of the Rift Valley
• Lake Victoria Basin
• Parts of the Rift Valley
• Nairobi County
• Isolated sections of the Highlands East of the Rift Valley
• Southeastern lowlands
• Isiolo County

A comparison with the previous week, from March 3 to March 9, indicated a significant increase in rainfall intensity, particularly in the Southeastern lowlands and sections of the Northeastern regions.

Upcoming Onset Dates for Other Regions

The Kenya Met Department anticipates that the remaining parts of the Highlands East of the Rift Valley and Southeastern lowlands will experience the onset of the long rains between March 18 and March 24.

Northeastern Kenya is also expected to receive rains during this period, extending into the following week from March 25 to March 31.

However, Gikungu warned that these regions could experience intermittent dry spells following the initial rainfall.

Northwestern Kenya and coastal areas are forecast to receive occasional showers throughout the rest of March. Despite these rains, they may not meet the official criteria to mark the onset of the season.

“The peak of the rainy season for the coastal region is projected to occur in May, with the onset likely happening in April,” Gikungu explained.

Residents Urged to Stay Alert

The KMD forecasts continued rainfall in the coming weeks, with isolated heavy showers anticipated in several areas. Regions likely to experience significant rainfall include:

• Highlands East and West of the Rift Valley (including Nairobi County)
• Lake Victoria Basin
• Rift Valley
• Southeastern lowlands
• Northeastern Kenya

Authorities have urged residents in these areas to stay vigilant and take precautionary measures against potential flooding and related hazards.