Why Indian cities remain hot even after the monsoon arrives

For many people in India, the arrival of the monsoon is supposed to bring relief from the intense summer heat. Dark clouds, rainfall and cooler winds usually signal the end of scorching temperatures. However, in recent years, many residents of cities such as Delhi, Mumbai, Ahmedabad, Hyderabad, Bengaluru and Kolkata have noticed something unusual. Even after the monsoon arrives, the weather often continues to feel extremely hot and uncomfortable.

Many people wonder why they still feel exhausted, sweaty and uncomfortable despite frequent rainfall. The answer lies in a combination of rising humidity, climate change and rapid urbanisation. Experts say these factors are working together to make Indian cities hotter than they were in the past.

While rain can temporarily lower temperatures, it does not always make the weather feel cooler. In many cases, the opposite happens. The air becomes more humid, making it harder for the human body to cool itself naturally.

Scientists believe that changing climate patterns and the way cities are expanding are creating conditions where people experience hotter days and warmer nights even during the monsoon season.

Humidity makes the heat feel worse

Many people assume that rainfall automatically brings cooler weather. While rain does reduce air temperature for a short period, it also increases the amount of moisture in the atmosphere. This rise in humidity can make the weather feel much hotter than the actual temperature shown on a thermometer.

The human body cools itself by sweating. When sweat evaporates from the skin, it removes heat from the body and helps maintain a comfortable temperature. However, when humidity is very high, the air is already full of moisture. As a result, sweat cannot evaporate easily.

Instead of cooling the body, sweat remains on the skin, leaving people feeling sticky, uncomfortable and tired. This is why a day with a temperature of 35 degrees Celsius can sometimes feel much hotter during the monsoon than a dry day with a similar temperature.

Meteorologists use a measurement called the heat index to understand this effect. The heat index combines air temperature and humidity to show how hot the weather actually feels to the human body.

In recent years, several Indian cities have recorded extremely high heat index values during the monsoon months. In some cases, conditions have felt as hot as 46 to 50 degrees Celsius despite regular rainfall.

High humidity not only causes discomfort but can also create serious health risks. People may suffer from dehydration, heat exhaustion and heatstroke because their bodies struggle to release excess heat.

Children, elderly people, outdoor workers and individuals with existing health conditions are especially vulnerable. Experts warn that humid heat can often be more dangerous than dry heat because many people underestimate its impact.

Research has shown that dangerously humid days are increasing across India. Scientists have found that the number of days with extremely high humidity and heat has risen significantly over the past several decades.

One reason behind this trend is the warming of the Arabian Sea and the Bay of Bengal. Warmer oceans release more moisture into the atmosphere, which is then carried inland by weather systems. This increases humidity levels across large parts of the country.

As a result, many cities are experiencing more days when the weather feels oppressive and uncomfortable, even when temperatures are not at record levels.

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Cities are trapping more heat

Climate change is only part of the problem. Experts say rapid urbanisation is making Indian cities much hotter through a phenomenon known as the Urban Heat Island effect.

As cities grow, natural landscapes are replaced by concrete buildings, asphalt roads, glass structures and other artificial surfaces. These materials absorb large amounts of heat during the day and release it slowly after sunset.

In rural areas, trees, soil and vegetation help cool the environment naturally. In contrast, urban areas store heat and continue releasing it throughout the night.

This is one reason why many cities no longer cool down properly after sunset. Warm nights have become increasingly common across India, creating a new challenge for public health and urban planning.

Normally, cooler nights allow people, buildings and roads to recover from daytime heat. However, when nights remain warm and humid, the environment starts the next day already heated. This makes daytime temperatures rise faster and increases overall heat stress.

Several additional factors contribute to the Urban Heat Island effect. Air conditioners release hot air outdoors, traffic generates constant heat, industries emit thermal energy and densely packed buildings restrict natural airflow.

The loss of trees and green spaces also plays a major role. Trees provide shade and cool the surrounding air through a natural process called evapotranspiration. When parks, wetlands and open spaces are replaced by buildings and roads, cities lose one of their most effective cooling systems.

Studies suggest that urbanisation alone may account for a large share of the additional warming observed in many Indian cities. In rapidly growing urban areas, temperatures are rising faster than in nearby rural regions.

The impact extends beyond comfort. Hotter cities place greater pressure on electricity systems because people rely more heavily on air conditioners and cooling devices. Energy demand often remains high even during the monsoon season.

Health experts are also concerned about the long-term effects. Continuous exposure to hot and humid conditions can worsen heart disease, respiratory problems and kidney-related illnesses. Outdoor workers, including construction labourers, delivery personnel and street vendors, face particularly high risks because they spend long hours exposed to the weather.

Several cities have introduced Heat Action Plans to help protect residents during periods of extreme heat. Measures such as cooling centres, hospital preparedness and public awareness campaigns provide temporary relief.

However, experts believe long-term solutions are equally important. They recommend increasing urban tree cover, protecting wetlands, creating more green spaces, encouraging cool-roof technologies and improving city planning to reduce heat buildup.

The growing heat in Indian cities is no longer just a summer problem. It has become a year-round challenge that now extends into the monsoon season as well.

The uncomfortable weather many people experience after the arrival of the rains is the result of both global climate change and rapid urban growth. Unless cities adopt more sustainable and climate-friendly development practices, residents are likely to face hotter days, warmer nights and increasing humidity in the years ahead.

As India continues to urbanise, building cooler, greener and more resilient cities will be essential for protecting public health and improving quality of life for millions of people.