October 6, 06:55IOL

How El Niño can cause droughts, floods, and unusual weather conditions worldwide

The cabinet is preparing for the potential impact of the El Niño event in 2026–2027, warning of pressure on water security, agriculture, drought preparedness, and food reserves.

In recent weeks, South Africans have experienced periods of intense heat, thunderstorms, heavy rains, strong winds, and severe weather in a short time. This occurs against reports that El Niño affects different parts of the world in varying ways.

The Pacific Ocean is warming at an unusually high rate. The current El Niño already surpasses previous records and is expected to intensify toward its usual peak around December.

However, the consequences of El Niño are not uniform for everyone. The climate pattern can exert very different effects across the globe: some regions may experience drier conditions and increased fire risk, while others may face more intense precipitation and flooding. This is due to the relationship between the Pacific Ocean and the atmosphere above it.

The Link Between the Pacific Ocean and El Niño

Under normal conditions, trade winds blow from east to west across the tropical Pacific Ocean. These winds transport warm surface water to the western part of the Pacific Ocean, where it accumulates around Indonesia and adjacent territories. When warm water moves westward, cooler water from the ocean depths rises to the surface in the east. This process, known as upwelling, helps keep the eastern part of the Pacific Ocean significantly cooler than the western part.

The warmer western part of the Pacific Ocean also plays a crucial role in rainfall. Warm water promotes evaporation, saturating the air with moisture. The air over the warmer ocean becomes less dense and rises. As it rises, it expands and cools, leading to the condensation of water vapor into clouds and rain. This resulting circulation is part of what is known as the Walker Circulation.

Air rises over the warmer western part of the Pacific Ocean, spreads higher in the atmosphere, and then some of it moves eastward and sinks over the cooler eastern part of the Pacific Ocean. Near the surface, the air again moves westward under the influence of the trade winds. This pattern explains why areas around Indonesia and the western Pacific generally receive significant amounts of precipitation, whereas the eastern tropical Pacific and much of the coast of Peru are significantly drier.

The ocean and atmosphere reinforce each other. Warmer conditions in the western Pacific promote air uplift, while cooler conditions in the east stimulate air subsidence. This resulting circulation helps maintain the trade winds, which continue to push warm water westward and bring cooler water to the surface in the east. Scientists call this amplifying process the Bjerknes feedback.

What Changes During El Niño?

During El Niño, the normal pattern begins to change. The trade winds weaken. This means less warm surface water is transported to the western part of the Pacific Ocean, and more warm water remains in the central and eastern parts of the Pacific Ocean, while the western part may become relatively cooler.

The shift in warm water also changes where the most intense evaporation, air uplift, cloud formation, and precipitation occur. As warmer water shifts eastward, the zone of most intense rainfall also moves to the central and eastern parts of the Pacific Ocean. This can lead to wetter conditions in some areas of the eastern Pacific and surrounding regions, including the coast of Peru.

The consequences can vary greatly in the western Pacific. Because more air rises over the central and eastern parts of the Pacific Ocean, some air sinks over the western part. This sinking air inhibits cloud formation, meaning that areas like Indonesia and the surrounding western Pacific may experience much drier conditions than usual. These drier conditions can also increase the risk of forest and peat fires in Indonesia.

The weakening of the trade winds further affects the Walker Circulation. As the temperature difference between the western and eastern parts of the Pacific Ocean decreases, the pressure contrast that helps drive the trade winds also weakens. The result is a weakening and eastward shift of the Walker Circulation.

El Niño's Impact Beyond the Pacific Ocean

The influence of El Niño is felt not only in the Pacific Ocean and its vicinity. Changes in the location of rising air and precipitation can affect atmospheric conditions thousands of kilometers away. These connections can influence weather patterns in distant parts of the world.

When water vapor condenses into clouds, heat is released into the atmosphere. During El Niño, the shift in the main zone of moist air uplift and precipitation also changes where this atmospheric heating occurs. This can warm the middle and upper tropical atmosphere outside the Pacific Ocean.

In the Sahel region, on the southern edge of the Sahara, this can hinder the further rise of warm, moist air near the surface. This can suppress clouds that contribute to rainfall and promote drier conditions. Reduced cloud cover also allows more sunlight to reach the ground, contributing to further warming and drying.

El Niño can also generate large atmospheric waves when the main area of air uplift and precipitation shifts eastward. These waves can propagate far from the Pacific Ocean, influencing winds and storm tracks. Consequences can reach the United Kingdom, where El Niño may increase the likelihood of wetter and stormier conditions in autumn and early winter, and also raise the risk of colder spells later in winter. However, these links are less certain than some El Niño effects in the tropics, as UK weather is subject to the influence of several other atmospheric factors.

Why El Niño Doesn't Mean the Same Weather Everywhere

El Niño changes the probability of certain weather scenarios, but it does not dictate the weather in every location. Its influence can also interact with conditions in other oceans. For example, changes related to El Niño can interact with the Indian Ocean Dipole—the sea surface temperature difference between the western and eastern parts of the Indian Ocean. This pattern strongly influences rainfall in East Africa and parts of India.

As a result, El Niño can create a general trend towards certain conditions, while local weather systems continue to produce very different outcomes. For instance, Thailand generally tends towards drier conditions during El Niño. Nevertheless, some parts of the country, including Bangkok, experienced heavy rains and flooding in September. India showed a similar contrast: the monsoon was generally unusually dry, but some areas still experienced intense precipitation and flooding. The main takeaway is that El Niño does not simply cause one type of weather globally. Instead, the shift of warm water in the Pacific Ocean alters atmospheric circulation. This shift can move precipitation to some regions while suppressing it in others, and atmospheric connections can carry its influence much further. Local weather systems can still override these broader patterns, meaning a region that usually becomes drier during El Niño can still experience periods of intense rain and flooding.

South Africa and El Niño

We have established how El Niño affects different parts of the world, and South Africa is no exception. The National Disaster Management Centre (NDMC) has stated that the country should focus on preparation rather than waiting for possible consequences, as forecasts from the South African Weather Service (SAWS) indicate that the current El Niño could become exceptionally strong by the end of 2026 or the beginning of 2027. SAWS reported that its latest seasonal forecasts show an increased probability of below-average rainfall by mid-summer, as well as a 'very high probability' of above-average temperatures. The meteorological authority emphasized that El Niño should not be viewed as a catastrophe, but it is crucial for people to plan with this phenomenon in mind.

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iol.co.zaOctober 1, 10:07

Explanation of the El Niño phenomenon and its potential impact on daily life

The El Niño phenomenon may sound like a complex meteorological term, but its consequences can affect homes, farms, and food bills in South Africa. This guide explains what El Niño is and how it might influence temperature, rainfall, water reserves, and food prices.

For many residents of South Africa, El Niño sounds like a scientific term. Nevertheless, it has the capacity to influence simple aspects of life, such as the feeling of heat at home, the level of water in local reservoirs, crop yields, and product costs.

According to forecasts from the World Meteorological Organization (WMO), El Niño has already established itself and is expected to become very strong by the end of 2026. Forecasters suggest that this phenomenon will continue into early 2027, causing changes in global temperature and rainfall patterns.

What is El Niño?

It is necessary to consider the Pacific Ocean as a huge part of the global climate system. Periodically, parts of this ocean warm up more than usual, leading to changes in winds and the movement of air masses across the planet. This change can affect the weather thousands of kilometers away, and this is called El Niño. It is important to understand that this does not mean that all of South Africa will suddenly become dry or that every day will be extremely hot; weather is complex and influenced by other factors. However, El Niño is associated with an increased risk of hotter conditions and changes in precipitation patterns, including dry spells in South Africa. Furthermore, the current El Niño is expected to be particularly strong.

Will South Africa get hotter?

There is a high probability of rising temperatures. The WMO indicates that El Niño increases the risk of extreme heat events. Extreme heat poses a danger not only due to discomfort but also because it can be threatening, especially for the elderly, children, outdoor workers, and those sensitive to heat. High temperatures can make homes, schools, and workplaces unbearably hot. For an average family, this may require greater water consumption for cooling, increased time spent in the shade, and greater reliance on fans or air conditioning.

What about the rains?

This aspect is particularly significant for South Africa. El Niño is often associated with drier conditions in South Africa, although its impact is not absolutely uniform every time. This means that some regions of the country may receive less rainfall than necessary. Rain is important not only for hanging laundry outside; it replenishes reservoirs, feeds rivers, helps farmers grow crops, provides water for livestock, and supports community supplies for homes, businesses, and educational institutions. A lack of rainfall puts pressure on all these systems.

Farmers may feel it first

Imagine the process of planting maize after weeks of field preparation and waiting for rain. If the rain comes late, doesn't come at all, or occurs at an inappropriate time, the harvest can suffer. This is one of the main problems during an El Niño event. Farmers are heavily dependent on rainfall, especially those without sufficient irrigation capabilities. A dry season leads to reduced harvests. For livestock breeders, drought means a shortage of feed and water for animals. The consequences are not limited to the farm: if farmers produce less food, there is less available in the market, which puts pressure on food prices. South Africa faced something similar during a previous major El Niño event, when drought led to agricultural losses across South Africa.

Could your grocery bill be affected?

Theoretically, yes. It is important to remember that El Niño does not guarantee an automatic rise in food prices. Food prices depend on numerous factors, including fuel costs, transportation expenses, electricity, imports, the Rand exchange rate, global prices, and the volume of production by farmers. However, weather is one such factor. If drought damages crops, farmers may have less produce to sell, creating a shortage of certain goods. For households trying to save every cent, even a small increase in the price of staple foods can be significant.

Furthermore, there is the issue of water, which is one of the most serious during a prolonged drought. With low rainfall, reservoirs and rivers receive less water, and hot weather increases evaporation. People also tend to consume more water in hot weather. This creates a difficult situation: water inflow decreases while demand rises. Residents of South Africa who have experienced water restrictions know how quickly drought can become part of daily life, leading to shorter showers, restrictions on garden watering, pool issues, and increased strain on municipalities managing limited supplies.

There is another side to this story

El Niño does not mean that South Africa will experience one long, completely dry summer period. Even during an El Niño event, heavy rains and flooding are possible. This may seem paradoxical: how can the same weather pattern cause both drought and floods? The answer lies in the fact that El Niño alters large-scale weather patterns, but local weather can still vary greatly. One place might experience prolonged periods of insufficient rainfall, followed by a sudden downpour, which can lead to flooding, especially where drainage systems cannot cope.

Each El Niño event is unique, and other weather conditions can alter the intensity of its impact in different parts of South Africa.

What about fires?

Hot and dry conditions also create dangerous conditions for wildfires. When grass, vegetation, and other plants dry out, they become more susceptible to ignition. This threatens housing, farms, wildlife, and infrastructure. South Africa has already faced the consequences of drought and wildfires during past El Niño events.

What should ordinary South Africans do?

There is no need to panic. El Niño is a warning to prepare, not a guarantee of disaster. Families should monitor meteorological warnings, use water sparingly, and take heat warnings seriously. Farmers are advised to use seasonal forecasts when making decisions regarding planting and livestock. Municipalities should prepare for potential pressure on water resources, and health authorities should prepare for periods of extreme heat. Reliable forecasts and early warnings give communities the opportunity to act before extreme weather turns into a crisis. This may be the most important thing to remember. El Niño may begin thousands of kilometers away from South Africa in the Pacific Ocean, but its consequences ultimately reach things that matter to South Africans every day.