Is India Entering a New Climate Reality Where Heatwaves and Humid Monsoons Are Becoming Silent Killers?

Is India Entering a New Climate Reality Where Heatwaves and Humid Monsoons Are Becoming Silent Killers?

KAKALI DAS

Heat is often called a silent killer, and that is not an exaggeration. Experts warn that even a single heatwave, sometimes lasting only a few days, can take tens of thousands of lives in a country like India. We are living in a time where stepping outside in extreme heat can become dangerous, not just uncomfortable. Every summer, we complain about rising temperatures. We tell each other to drink water, stay in the shade, and avoid the sun. Then we move on. But have we really understood what heat is doing inside our bodies? How long before a normal hot day turns into something our bodies simply cannot handle?

To understand this, we need to go back to a basic idea we learned in school. Human beings are warm blooded. This means that our bodies try to maintain a constant internal temperature, usually between 36.5 and 37.5 degrees Celsius. This is a very narrow range, and every organ in the body depends on this balance to function properly. Whether you are walking in the cold mountains or in the hot streets of a city during summer, your body is constantly working to stay within this safe range.

This balance is controlled by a small but very important part of the brain called the hypothalamus. You can think of it as the body’s thermostat. When it senses that the outside temperature is rising, it activates cooling systems to protect you. The body mainly uses two methods to cool itself down.

The first method is sweating. When your body temperature rises, your sweat glands produce sweat. As this sweat evaporates from your skin, it takes heat away from your body. This is one of the most effective ways the body cools itself.

The second method is called vasodilation. In simple terms, your blood vessels expand, and more blood flows closer to the surface of your skin. This allows heat to escape into the air. Together, sweating and increased blood flow help your body stay cool even in hot conditions.

The human body is very efficient at managing heat, but it is not limitless. When the temperature outside keeps rising for long periods, the system becomes overworked. The hypothalamus struggles to keep up, and the body starts to show signs of stress. This is when heat exhaustion begins.

The early signs of heat exhaustion are often ignored. You may start sweating heavily and feel extremely tired. This is your body’s way of telling you to slow down. It is trying to prevent further heat production from physical activity. But heavy sweating also means you are losing water and important salts. If these are not replaced, dehydration begins.

At this stage, you may feel very thirsty. Your skin might feel cold and sticky, almost like you are covered in a damp cloth. You may also experience muscle cramps, especially in your legs or stomach. These cramps happen because your body is losing essential salts through sweat.

Another effect of heat is on your blood pressure. As your blood vessels expand, your blood pressure can drop. This can make you feel dizzy, weak, or nauseous. You might feel like your head is heavy or that you are about to faint. To compensate for this, your heart starts beating faster and harder to keep blood flowing to vital organs. This puts a lot of strain on the heart, especially in older people or those with existing health conditions. In some cases, this strain can lead to serious problems like heart attacks.

If heat exhaustion is not treated, it can turn into heat stroke, which is a medical emergency. Heat stroke means that the body’s cooling system has failed completely. At this point, the body is no longer able to regulate its temperature.

One of the most dangerous signs of heat stroke is that the body may stop sweating. The skin becomes hot, red, and dry. The person may become confused, speak slowly, or even have seizures. This is a life threatening condition and requires immediate medical attention.

To understand how risky heat can be, we need to look at temperature more closely. Studies show that when the outside temperature crosses 35 degrees Celsius, the body starts working much harder. Breathing becomes faster, and the heart rate increases. At around 40 degrees, the body uses nearly 35 percent more energy just to stay cool, even if you are sitting still.

But temperature alone does not tell the full story. There is another factor that makes heat much more dangerous, and that is humidity. Many people notice that a very hot day in a dry city feels different from a slightly less hot day in a coastal city. This is because of the moisture in the air.

In dry heat, sweat evaporates quickly, which helps cool the body. But in humid conditions, the air is already full of moisture. This means sweat cannot evaporate easily. Instead, it stays on your skin, and the cooling effect is reduced. As a result, your body struggles more to release heat.

This is why humidity acts like a multiplier. A temperature of 34 degrees with high humidity can feel like 45 or even 50 degrees. This is known as the “feels like” temperature. It is not just the number on your phone that matters, but how hot it actually feels to your body.

A recent 2026 article titled “Anatomy of moist heatwaves in India during the summer monsoon season, Climate Dynamics” also indicates that humid heat is not limited to summer anymore. With changing climate patterns, even the monsoon season is becoming more dangerous. The combination of heat and humidity during this time can put people at serious risk.

When we talk about heat, we often think only about extreme situations like fainting or heat stroke. But heat also affects the body in less obvious ways over time. These effects are often ignored, but they can be just as serious.

One common effect is on digestion. Many people notice that their appetite decreases during summer. Even a normal meal can feel too heavy. This happens because the body sends more blood to the skin for cooling. As a result, the digestive system receives less blood, and digestion slows down. This can lead to bloating, acidity, cramps, and loss of appetite.

Hot weather also creates ideal conditions for bacteria to grow. Food spoils faster, which increases the risk of infections like diarrhea and typhoid. Many cities report a rise in stomach related illnesses during summer for this reason.

Heat also affects mental health. People often feel more irritable during hot weather, and this is not just because of discomfort. High temperatures can affect the chemicals in the brain that control mood. They can increase stress hormones and reduce blood flow to the brain. This can lead to anxiety, poor sleep, and difficulty concentrating.

There is even a term for this, heat anxiety. For people who already struggle with mental health issues, heat can make symptoms worse. It can make it harder to cope with daily life.

Long term exposure to heat can cause even more serious problems. One major concern is its effect on the kidneys. When you sweat a lot and do not drink enough water, your blood becomes thicker. Your urine becomes darker, and you may urinate less often. Over time, this can lead to the formation of kidney stones and urinary infections.

Repeated dehydration and heat stress can also damage the kidneys permanently. In many parts of India, doctors are now seeing cases of kidney failure in relatively young men. Many of them work in outdoor jobs such as construction, farming, or sanitation. Their main risk factor is long hours in the heat without proper hydration.

Similar patterns have been seen in other parts of the world. Many migrant workers in hot regions have developed chronic kidney disease due to extreme working conditions and prolonged exposure to heat.

The scale of the problem is growing. Heatwaves are becoming more frequent and more intense. A large number of districts in India are now considered high risk for extreme heat. Thousands of heat related illnesses are reported every year, but the real numbers may be much higher. Heat related deaths are often recorded as heart attacks or strokes, making it difficult to measure the true impact.

It is also important to understand that heat does not affect everyone equally. Certain groups are more vulnerable. These include the elderly, children, pregnant women, and people with existing health conditions like diabetes or heart disease. Their bodies are less able to handle the stress caused by heat.

However, the most affected are often those who cannot avoid it. Delivery workers, street vendors, construction workers, and many others spend long hours in direct sunlight. For them, heat is not just a seasonal discomfort but a daily risk.

Despite all this, there are steps we can take to protect ourselves and others. The most important step is to stay hydrated. Drinking enough water is essential, but it is also important to replace lost salts. Drinks like oral rehydration solutions, coconut water, lemon water, and buttermilk can help maintain balance in the body. At the same time, it is better to avoid drinks like alcohol and excessive caffeine, as they can increase dehydration.

Food choices also matter. Instead of heavy meals, it is better to eat smaller and lighter meals throughout the day. Fresh and easily digestible foods are ideal. It is also important to avoid stale or spoiled food.

Reducing exposure to direct sunlight is another key step. The hottest part of the day is usually between late morning and afternoon. Staying indoors or in shaded and well ventilated areas during this time can reduce risk.

Clothing also plays a role. Light coloured, loose fitting clothes help reflect heat and allow sweat to evaporate. Tight or dark clothing can trap heat and make the body feel hotter.

Simple cooling methods can also help. Taking cool showers, using fans, and applying cold packs to areas like the neck and underarms can bring down body temperature.

At the same time, it is important to recognize the signs of heat related illness in others. If someone shows symptoms of heat stroke, immediate action is needed. Move them to a cooler place, loosen their clothing, and try to cool their body with water or ice. But most importantly, seek medical help without delay.

Heat is dangerous, but it is not unbeatable. Awareness can save lives. Understanding how the body reacts to heat and recognizing early signs of trouble can make a big difference. As temperatures continue to rise, this knowledge becomes not just useful, but essential for survival.

The heat may be silent, but with the right awareness and action, we do not have to be.

References

1. World Health Organization (WHO). Heat and Health. WHO India Climate and Health Unit, 2023–2025.
2. De Bont, J. et al. (2024). Impact of heatwaves on mortality in India. Environment International. Elsevier.
3. Ambika, A. et al. (2024). Global warming amplifies outdoor extreme moist heat during the Indian summer monsoon. Earth’s Future. American Geophysical Union.
4. Deoras, A. et al. (2026). Anatomy of moist heatwaves in India during the summer monsoon season. Climate Dynamics. Springer Nature.
5. Sudharsan, P. et al. (2025). Increasing risk of oppressive heatwaves over India under climate change.

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