For many Kenyans, the mere mention of El Nino brings in mind flooded roads, washed-away homes and devastating losses.
But weather experts say one of the country’s biggest climate misconceptions is that El Nino automatically translates into catastrophic floods.
According to the Kenya Meteorological Services Authority (KMSA), formerly the Kenya Meteorological Department, El Nino is only one of several climate drivers that influence Kenya’s weather, and whether the country experiences above-average rainfall depends largely on another phenomenon much closer to home, the Indian Ocean Dipole (IOD).
While speaking to the Star, Hannah Kimani, Assistant Director of Public Weather Services at KMSA, explained that El Nino is a naturally occurring climate phenomenon that develops in the Pacific Ocean when sea surface temperatures in the central and eastern Pacific become warmer than normal, while the western Pacific becomes cooler.
“El Nino is a natural climate variability. It is classified as weak, moderate, strong and very strong. There is nothing called a ‘super El Nino.’ It is one phase of what scientists call the El Nino Southern Oscillation, which also includes the neutral phase and La Nina, the cool phase,” she said.
She noted that although the phenomenon originates thousands of kilometres away in the Pacific Ocean, its effects extend across the globe because the world’s oceans and atmosphere are interconnected.
For East Africa, however, the Indian Ocean often determines whether El Nino’s influence translates into heavy rainfall.
“When we have El Nino in the Pacific, the Indian Ocean often responds by developing what we call a positive Indian Ocean Dipole. This creates warmer than normal waters over the western Indian Ocean near the East African coast and cooler waters near Australia, providing the conditions for increased rainfall over Kenya and the wider region,” Kimani explained.
She cautioned that El Nino should not be confused with rainfall itself.
“El Nino is not rainfall. It is one of the drivers that changes global temperature and precipitation patterns. Whether Kenya experiences heavy rainfall depends on several factors, especially the behaviour of the Indian Ocean Dipole,” Kimani said.
The distinction, she said, explains why not every El Nino event has resulted in devastating floods.
One of the clearest examples was the 2015 El Nino. Although it ranked among the strongest on record, Kenya experienced relatively modest rainfall because the accompanying positive Indian Ocean Dipole was weak.
“In 2015 we had a very strong El Nino, but the response of the Indian Ocean was weak. That is why the country did not receive the kind of rainfall experienced during the 1997 or 2023 events,” she said.
By contrast, both the historic 1997-98 El Nino and the 2023 event were accompanied by strong positive Indian Ocean Dipole conditions, resulting in widespread flooding across many parts of Kenya.
Kimani pointed out that the strongest positive Indian Ocean Dipole on record occurred in 2019, even without a major El Nino event, yet it still triggered exceptionally heavy rainfall that caused flooding across the country and extended into early 2020.
“That tells you that El Nino is not the only factor that causes above-average rainfall. For East Africa, the Indian Ocean Dipole is an equally important driver,” she said adding that, globally, El Nino occurs every two to seven years and lasts between nine and 12 months.
Scientists have monitored the phenomenon for decades, with historical records dating back to the 1950s.
“Since the devastating 1997-98 event, Kenya has experienced seven El Nino episodes, but only a few produced severe flooding because the intensity of rainfall depended on the interaction between El Niño and the Indian Ocean Dipole,” said Kimani.
The World Meteorological Organization notes that El Nino alters rainfall and temperature patterns across much of the globe. While East Africa often becomes wetter during some El Nino episodes, countries such as Australia and parts of southern Africa frequently experience drought, highlighting that the phenomenon affects different regions in different ways.
Kimani said the 2026 El Nino has already developed and is currently influencing weather patterns across Kenya.
“It is already present. We are not debating whether El Nino exists, it is there,” she said.
According to KMSA, the current El Nino has contributed to the warmer than usual temperatures experienced across Nairobi, central Kenya and parts of western Kenya during what is normally the coolest period of the year. It has also contributed to below-average rainfall over western Kenya and the North Rift between June and September.
Forecasts indicate an 81 per cent probability that the current El Nino could strengthen into a very strong event later this year. At the same time, there is more than a 90 per cent probability that a positive Indian Ocean Dipole will develop, although meteorologists continue to monitor the situation.
Rather than creating panic, Kimani urged Kenyans to use the forecasts as an opportunity to prepare.
“We do not want to create fear because above-average rainfall also has significant benefits. Full dams improve hydropower generation, farmers can benefit from adequate soil moisture, and communities can harvest rainwater for future use.”
She called on both national and county governments to work closely with meteorologists in promoting climate-smart agriculture, improving drainage systems, strengthening early warning systems and advising farmers on suitable crop varieties for wetter conditions.
At the household level, she encouraged Kenyans to embrace what disaster experts describe as, no-regret actions. “If you buy a water tank today and, for one reason or another, the rains are less than expected, you will still have made a worthwhile investment because you can harvest rainwater for many years to come,” she said.
The Kenya Meteorological Services Authority is expected to convene the National Climate Outlook Forum later this month or in early September, bringing together experts from agriculture, water, health, disaster management and other sectors to review the latest seasonal forecasts and develop sector-specific advisories.
“As the country prepares for the October-December short rains, the focus should not be on fearing El Nino, but on understanding what it means, monitoring the Indian Ocean Dipole and taking early action to reduce risk while maximising the opportunities that favourable rainfall can bring,” Kimani added.