NAIROBI, Kenya — Kenya is expected to receive above-normal rainfall in most parts of the country during the October-December season, but the intensity of the rains will depend largely on conditions in the Indian Ocean rather than El Niño alone.
Kenya Meteorological Service Authority (KMSA) principal meteorologist Jemima Gacheru said the country should expect heavy rains in many areas but warned against assuming that the season will automatically resemble the devastating 1997 rains simply because the world is experiencing a strong El Niño.
She said the Indian Ocean Dipole (IOD) — a climate pattern driven by differences in sea-surface temperatures between the western Indian Ocean near East Africa and the eastern Indian Ocean near Indonesia — will be a major factor in determining how much rain Kenya receives.
“So this is just to demystify that notion that El Niño is always equal to rainfall. That is not always the case,” Gacheru said during a KMSA webinar.
Indian Ocean Holds Key to Rainfall
Gacheru said Kenya has previously experienced strong El Niño seasons that did not produce exceptionally heavy rainfall because conditions in the Indian Ocean were not favourable.
A positive IOD, which occurs when waters in the western Indian Ocean near East Africa are warmer than normal relative to the eastern Indian Ocean, is generally associated with increased rainfall over East Africa.
Gacheru said the IOD was currently showing positive conditions and could strengthen as the October-December season progresses.
“It is currently positive at 0.7 degrees Celsius, and it is expected that as we go into the October, November, December season, it will rise to a maximum value of 1.0 degrees, particularly in October,” she said.
However, the Australian Bureau of Meteorology reported a weekly IOD index of +0.65°C for the week ending September 13, while classifying the IOD as neutral because a single observation above +0.4°C is not enough to establish a positive IOD event.
Why 1997 Was Different
Gacheru pointed to 1997 as an example of how El Niño and the IOD can combine to produce exceptional rainfall.
That year was characterised by a strong El Niño and a strong positive IOD, with the IOD reaching about 1.4°C in November 1997.
Kenya subsequently experienced heavy rainfall across much of the country.
The situation was different in 2015, when Kenya also experienced a strong El Niño but the IOD was only around 0.5°C.
Rainfall that year was more mixed, with some areas recording above-normal rainfall, others near-normal conditions and some receiving below-normal rainfall.
Gacheru said the current outlook therefore should not be interpreted as a repeat of 1997.
Most Counties to Receive Above-Normal Rain
Despite the uncertainty over the eventual strength of the IOD, Gacheru said the current forecast indicates that most counties are likely to receive above-normal rainfall.
She cautioned, however, that above-normal rainfall does not mean every part of the country will receive the same amount of rain or experience the same distribution.
“Most areas are expected to have fair to good distribution, meaning the dry spells will not be as many,” she said.
Some arid and semi-arid areas could experience a different pattern.
Gacheru said Turkana and Samburu could see the rains begin around the third or fourth week of October and continue until the first week of December, with rainfall distribution potentially remaining poor.
Farmers Urged to Prepare for Rains
The expected rainfall could provide an opportunity for farmers to improve food production by taking advantage of increased soil moisture.
Ruth Njeri, a senior agricultural officer in the State Department for Agriculture’s Climate Change Unit, said farmers should prepare to maximise the benefits of the anticipated rains.
“This will give us maximum soil moisture utilisation, which our farmers are encouraged to take advantage of,” Njeri said.
She added that the rains could also support water storage, long-term aquifer recharge and the rebuilding of household food stocks.
Livestock farmers could similarly benefit if rainfall is sufficiently well distributed.
Heavy Rains Could Also Bring Risks
Agricultural authorities warned that increased rainfall could also create serious risks for farmers.
Njeri said excessive water could cause flash floods, crop destruction, pest and disease outbreaks, and post-harvest losses.
Flooding and prolonged humidity can increase the risk of mould and flood-related toxins in stored produce, while wet conditions can create favourable environments for crop pests, diseases and weeds.
Farmers therefore face the challenge of preparing not only for adequate rainfall but also for possible excess water and its effects on crops and livestock.
Government Steps Up Flood Preparedness
The Government has also begun preparing for possible flooding and other weather-related impacts.
Dr Sally Kimosop, Environment Secretary in the Ministry of Environment, Climate Change and Forestry, urged Kenyans to treat the forecast as a call for early action rather than panic.
“El Niño is a climate phenomenon, but a disaster is not inevitable,” Kimosop said.
She stressed that early preparation could reduce the human and economic cost of extreme weather.
The National Disaster Operations Centre has identified the Tana and Victoria basins, together with landslide-prone areas, for anticipatory measures including flood monitoring and early-warning systems.
