The Kenya Meteorological Department has forecast rainfall in parts of 32 counties between September 29 and October 5. According to the department's weekly forecast, rainfall is likely in parts of Lamu, Kwale, Kilifi, Mombasa, Tana River, Taita Taveta, Mandera, Marsabit, Meru, Embu, Garissa, Kiambu, Kirinyaga, Kisumu, Kitui, Laikipia, Machakos, Makueni, Murang'a, Nairobi, Nakuru, Nyandarua, Nyeri, Tharaka-Nithi, Trans Nzoia, Bungoma, Elgeyo Marakwet, Bomet, Kericho, Kisii, Nyamira and Wajir counties.
The forecast follows rainfall recorded in several parts of the country between September 21 and 27. During the period, rainfall was recorded in Bungoma, Busia, Migori, Siaya, Nyamira, Kakamega, Kisii, Nakuru and Kericho. Kibabii University rainfall station in Bungoma recorded the highest seven-day rainfall total at 125.1mm. Miyare rainfall station in Migori County recorded the highest rainfall amount within 24 hours, with 61.2mm on September 21.
Meteorologists continue to assess how ocean conditions will influence rainfall during the October-December period. A principal meteorologist at the Kenya Meteorological Service Authority, Jemima Gacheru, said El Niño alone cannot determine how much rain Kenya will receive. She noted that the Indian Ocean Dipole, which measures differences in sea temperatures between the western Indian Ocean near East Africa and the eastern Indian Ocean near Indonesia, was also important.
Gacheru said the Indian Ocean Dipole index was currently at 0.7 degrees Celsius and was expected to rise to about 1.0 degrees in October. However, the Australian Bureau of Meteorology reported a weekly Indian Ocean Dipole index of +0.65°C for the week ending September 13, classifying it as neutral and noting that one observation above +0.4°C does not establish a positive event.
The strength of the Indian Ocean Dipole could determine whether Kenya experiences extremely heavy rainfall or a more mixed pattern. Gacheru cited 1997, when a strong El Niño and strong positive Indian Ocean Dipole coincided with heavy rainfall across most of Kenya. In 2015, strong El Niño conditions occurred alongside a weaker Indian Ocean Dipole of about 0.5 degrees, resulting in a mixed rainfall pattern.
Gacheru said the current forecast expected most counties to receive above-normal rainfall, although this would not mean the same amount of rain would fall everywhere. She noted that most areas were expected to have fair to good distribution, meaning the dry spells would not be as many. The forecast is crucial for farmers and other stakeholders who rely on rainfall for their livelihood.
The Kenya Meteorological Department's forecast is based on various indicators, including the El Niño-Southern Oscillation and the Indian Ocean Dipole. The department will continue to monitor the situation and provide updates as necessary. Farmers and other stakeholders are advised to take necessary precautions to mitigate the effects of the expected rainfall.
Key points
- Rainfall expected in 32 counties between September 29 and October 5
- Indian Ocean Dipole index currently at 0.7 degrees Celsius
- Most counties expected to receive above-normal rainfall
