As temperatures rise across Nigeria, extreme heat can do more than cause discomfort. From dehydration and disrupted sleep to heat exhaustion and potentially life-threatening heatstroke, understanding how the body responds to high temperatures can help people recognise the warning signs and protect their health.

Heat makes ordinary activities feel exhausting. A short walk under the afternoon sun becomes uncomfortable, concentration begins to slip, and returning home does not always bring relief. For others, particularly those who work outdoors or live with existing medical conditions, prolonged exposure to high temperatures can become a serious health risk.

As Nigeria transitions from the rainy season into the hotter, drier months, the Nigerian Meteorological Agency (NiMet) has warned of rising temperatures and increased heat discomfort. In an advisory reported on October 23, the agency recommended regular water consumption, lightweight clothing, and reduced exposure to direct sunlight during the hottest periods of the day. It also urged schools and workplaces to provide drinking water, adequate ventilation and shaded rest areas.

The changing weather also comes as meteorologists monitor a strengthening El Niño. El Niño occurs when sea surface temperatures in the central and eastern equatorial Pacific become warmer than usual, influencing weather patterns in other parts of the world.

The World Meteorological Organisation (WMO), in an update published on September 3, 2026, said the climate phenomenon was expected to intensify in the coming months, with possible effects on temperature and rainfall patterns and increased risks of extreme weather.

The United States National Oceanic and Atmospheric Administration (NOAA), in its October 8 update, reported that a strong to very strong El Niño was likely to continue into early 2027. However, the WMO cautions that the strength of an El Niño event alone does not determine the severity of its effects in a particular country. Its impact varies by location and season and can be influenced by other climate patterns. The forecasts therefore provide important global context, but do not establish El Niño as the direct cause of the heat currently experienced in Nigeria.

How the body responds to heat
Under normal conditions, the body regulates its internal temperature through mechanisms including sweating and changes in blood flow to the skin. When temperatures rise, sweating helps release heat as moisture evaporates from the skin. However, high humidity makes evaporation less efficient, while physical exertion generates additional heat.

When the body cannot lose heat quickly enough, its internal temperature can rise, increasing the risk of heat-related illness. Prolonged exposure can also place additional strain on the heart and kidneys, according to the WHO.

When heat becomes dangerous
One of the most immediate dangers is dehydration, which occurs when the body loses more fluid than it takes in. Excessive sweating, inadequate fluid intake and prolonged outdoor activity can contribute to the condition.

Thirst, dark-coloured urine, reduced urination, dizziness and tiredness may indicate dehydration. If fluid loss continues, a person may experience weakness and difficulty carrying out ordinary activities.

Heat exhaustion is another concern. It can develop after prolonged exposure to high temperatures, particularly when someone is physically active or sweating heavily. Symptoms may include headache, nausea, dizziness, weakness and excessive sweating.

Heatstroke is more dangerous. It occurs when the body’s temperature regulation fails and can cause damage to the brain and other organs. Confusion, seizures, collapse or loss of consciousness in someone exposed to extreme heat are emergency warning signs. Emergency medical assistance should be sought immediately while rapid cooling is started.

In an October 25 report by the International Centre for Investigative Reporting, Dr Yetunde Odusolu, a consultant public health physician at Ikorodu General Hospital, Lagos, identified dehydration, heat exhaustion, heatstroke, cardiovascular strain, and kidney complications among the risks associated with prolonged heat exposure.

Odusolu emphasised the need to recognise severe symptoms. “Heatstroke is a medical emergency, especially when a person develops confusion, collapse or altered consciousness. Seek emergency care immediately and begin safe cooling while help is arranged,” she said.

Other effects on health
The impact of extreme heat is not limited to conditions that develop after spending hours in the sun. High temperatures can also aggravate existing illnesses.

The WHO identifies cardiovascular disease, diabetes, respiratory conditions, kidney disease and some mental health conditions among the health concerns that can be worsened by heat. The strain placed on the body as it attempts to cool itself can contribute to acute kidney injury and other complications.

For people living with chronic illnesses, extreme heat may therefore require additional precautions. Some medications can also affect sweating, fluid balance or the body’s ability to regulate temperature. People taking regular medication should consult their healthcare providers about appropriate precautions rather than changing or stopping treatment themselves.

Sleep is another consideration. When indoor temperatures remain high at night, the body may struggle to recover from daytime heat exposure. Poor sleep can leave people tired and less able to concentrate during the day. Repeated exposure to uncomfortable nighttime temperatures may compound the strain.

The effects can be particularly challenging in densely built urban areas, where buildings and roads absorb heat during the day and release it later. The WHO notes that the loss of green spaces and the use of building materials that retain heat can increase people’s exposure to high temperatures.

In Lagos, humidity adds another complication. Even when temperatures are lower than those recorded in northern Nigeria, moisture in the air can make it harder for sweat to evaporate, reducing the body’s ability to cool itself efficiently.

Who is most at risk?
Although anyone can develop a heat-related illness, the risks are not evenly distributed. Infants and young children, older adults, pregnant women and people with chronic illnesses are among those who require particular attention. People with disabilities, those living alone and individuals who have difficulty recognising or responding to thirst may also need additional support.

Outdoor workers face another challenge. Market traders, construction workers, farmers, traffic officers and sanitation workers may spend prolonged periods in the heat, sometimes with limited access to shade or drinking water.

Housing and income also influence exposure. People living in poorly ventilated rooms may struggle to find relief even after returning home, while unreliable electricity can limit access to mechanical cooling.

The WHO identifies outdoor and manual workers as particularly susceptible to heat stress. It also notes that people on lower incomes may face disproportionate exposure because of inadequate housing and limited access to cooling.

The consequences are not only physical. Research published in Environmental Research: Health in June 2026 examined the perceived effects of extreme heat on health and livelihoods among 368 Nigerian adults. The study found that 33 per cent of male respondents and 26 per cent of female respondents reported that extreme heat always or usually affected their physical health. Mental health and financial wellbeing were also affected among some participants.

The researchers cautioned that the study relied on self-reported experiences and that its findings should not be treated as representative of every Nigerian adult. Nevertheless, the results highlight how heat can affect several aspects of everyday life beyond immediate medical emergencies.

How to stay safe
Reducing exposure is one of the most effective ways to lower the risk of heat-related illness.

NiMet advises Nigerians to drink water regularly, wear lightweight, breathable clothing and limit prolonged exposure to direct sunlight. Where possible, strenuous activities should be moved to cooler periods of the day.

The WHO recommends spending time in a cool place, taking cool showers or baths, using damp cloths to cool the skin and wearing light, loose-fitting clothing. It also advises people to check on older relatives, neighbours and others who may be particularly vulnerable during periods of extreme heat.

Keeping indoor spaces cool requires attention to changing outdoor conditions. When the outside air becomes cooler than the air indoors, opening windows can help ventilate the home. During hotter periods, shading windows from direct sunlight can reduce indoor heat gain.

Fans can improve comfort in many conditions, but they should not be relied on as the sole cooling measure in extreme temperatures. The WHO advises against using electric fans when air temperatures exceed 40°C because they can increase heat exposure.

Hydration needs vary with activity, health and environmental conditions. People who sweat heavily may need additional fluids, while those with medical conditions requiring fluid restrictions should follow their healthcare provider’s advice.

Employers also have a role to play. Providing drinking water, shaded rest areas, regular breaks and opportunities to reduce strenuous activity during the hottest periods can help protect outdoor workers.

When to seek help
Extreme heat should not be dismissed as an ordinary inconvenience when symptoms begin to appear.

Persistent dizziness, weakness, headache, nausea or heavy sweating may signal heat-related illness. Anyone experiencing these symptoms should stop strenuous activity, move somewhere cooler and begin cooling down.

Confusion, seizures, collapse or loss of consciousness require emergency medical assistance. A person showing signs of heatstroke should be cooled rapidly while help is arranged. Do not give fluids to someone who is unconscious or unable to swallow safely.

Children should never be left alone in parked vehicles, even briefly, because temperatures inside can rise rapidly.

As Nigeria enters the hotter months, recognising the health risks of extreme heat becomes an important part of everyday self-care. Drinking water, adjusting outdoor activities, keeping living spaces cool and checking on vulnerable people are practical measures, but they must be supported by accessible health information, safer working conditions and effective public heat warnings.

Extreme heat may be unavoidable, but its most serious consequences are not inevitable. Early recognition, appropriate precautions and prompt medical attention can help protect health when temperatures rise.

Tips for staying safe in extreme heat

Drink water regularly
Do not wait until you feel thirsty. If you have a medical condition that requires limiting fluids, follow your healthcare provider’s advice.

Avoid strenuous activity during the hottest hours
Exercise and carry out physically demanding tasks during cooler parts of the day where possible.

Wear light clothing
Choose loose-fitting, breathable fabrics that help keep you comfortable.

Keep your home cool
Shade windows from direct sunlight and ventilate rooms when the outdoor air is cooler than the air indoors.

Take cool showers or use damp cloths
These can help lower your body temperature and improve comfort.

Take breaks in the shade
If you work outdoors, rest regularly and drink water throughout the day.

Check on vulnerable people
Pay particular attention to young children, older adults, pregnant women and people living with chronic illnesses.

Recognise warning signs
Dizziness, nausea, weakness and headaches may indicate heat-related illness. Confusion, seizures or collapse require emergency medical attention.

Never leave children in parked vehicles
Temperatures inside a vehicle can rise rapidly, even when it does not feel exceptionally hot outside.

Do not rely on fans in extreme heat
The WHO advises against using electric fans when air temperatures exceed 40°C because they can increase heat exposure.