The month of March marks the start of the long rains season, and the Kenya Meteorological Department says the onset of the rains could occur earlier than anticipated.
The Weatherman is attributing the early onset in some parts of the country to a system known as the Madden Julianne Oscillation (MJO).
This is a band of rain-bearing clouds that move across the tropical oceans and bring rainfall to the country. This effect is usually felt beginning in the second phase of the Madden Julianne Oscillation, expected in the second week of March, leading to an earlier onset to the season than the anticipated onset over some parts of the country.
“The rainfall forecast for March 2025 is based on regression of Sea Surface Temperature Anomalies (SSTAs) on the March rainfall as well as Sea Surface Temperature (SST) gradients,” says the Director of Kenya Meteorological Service Dr. David Gikungu and adds, “One of the features of interest is the Madden Julianne Oscillation (MJO), a band of convective clouds that moves across the tropical oceans and brings rainfall to the country when it is in phases two, three and part of phase four.”
Dr. Gikungu says that it is expected that Madden Julian Oscillation will be in phase two from the second week of March “and is likely to lead to an earlier than anticipated onset over some parts of the country.
The Weatherman says that the outlook for March 2025 indicates that near to above average rainfall is expected over the Lake Victoria Basin, the Highlands West of the Rift Valley, the Central and Southern Rift Valley, the Highlands East of the Rift Valley, including Nairobi County, the Southeastern lowlands, and isolated areas over Northeast and Northwest, near to below average rainfall is expected over the Coast, most of the Northeast and Northwestern regions.
In the statement, Dr. Gikungu says that “temperature is expected to be warmer than average over the entire country with higher probabilities over the Northeast, Northwest, Highlands East of the Rift Valley including Nairobi County and parts of the Coast and Southeastern lowlands.”
The onset for the Lake Victoria Basin, the Highlands West of the Rift Valley and the Central and South Rift Valley (Siaya, Kisumu, Homa Bay, Migori, Kisii, Nyamira, Trans Nzoia, Baringo, Uasin Gishu, Elgeyo Marakwet, West Pokot, Nandi, Laikipia, Nakuru, Narok, Kericho, Bomet, Kakamega, Vihiga, Bungoma and Busia): The onset of the long-rains season is expected from the second to third week of March.
The North-Western Region of Turkana and Samburu Counties, the onset of the long-rains season is expected from the first to second week of April.
The Highlands East of the Rift Valley and Central Kenya which includes the counties of Nairobi, Nyandarua, Laikipia, Nyeri, Kirinyaga, Murang’a, Kiambu, Meru, Embu and Tharaka Nithi, the onset of the long-rains season is expected from the second to third week of March, which may be followed by a short dry spell.
The North-Eastern Region in the counties of Mandera, Marsabit, Wajir, Garissa and Isiolo Counties, the onset is expected in the first to second weeks of April although “occasional rainfall is likely over a few areas from the second to third weeks of the month followed by a likely dry spell,” says Dr. Gikungu in the forecast and notes that, the expected rainfall amounts are likely to be near to below the long-term average for March “although parts of Mandera and Wajir that border Ethiopia and the southern parts of Marsabit may receive near to above average rainfall.”
In the South-Eastern Lowlands of Kajiado, Kitui, Makueni, Machakos and Taita Taveta, the onset of the long-rains season is expected from the second to third week of March which may be followed by a short dry spell, while in the Coastal Strip’s counties of Mombasa, Tana River, Kilifi, Lamu and Kwale, the onset is expected during the fourth week of March to the first week of April over the South Coast and second to third week of April over the North coast.
Among the anticipated impacts include; flash and riverine floods in poorly drained urban centers and along rivers, especially over the Highlands East of the Rift Valley, Nairobi, the Lake Victoria Basin, South Rift Valley, and the Southeastern lowlands. “Residents are advised not to walk, drive or cycle in moving waters to avoid loss of life,” says the weatherman.
The health sector is being advised to stock up medicines to deal with an anticipated increase in vector borne diseases in areas that are expected to receive near to above average rainfall especially, “over the Lake Victoria Basin as stagnant water coupled with warmer than average temperatures are likely to provide breeding grounds for mosquitoes,” he notes.
The Weatherman is urging motorists to be cautious as the rainfall could lead to slippery roads and poor visibility, especially on days with heavy rainfall. “Motorists are therefore advised to be careful on the roads to minimize accidents.”
