IIT Bombay finds why India's deadly heatwaves hit harder and start earlier now

India is facing severe heat before May, and IIT Bombay researchers say the real reason may be closer than we thought. Their study finds local land, humidity and sky conditions play a bigger role in triggering dangerous heatwaves across North India than travelling hot air alone.

In Short

• IIT Bombay says local weather and land conditions drive many heatwaves in North India
• Study finds moist and dry heatwaves behave differently but both can turn deadly fast
• Better city-wise warnings may be possible if forecasts track humidity, soil and clouds

Step outside in Delhi, Lucknow, Patna or Jaipur right now and it already feels like peak June. Large parts of India have seen temperatures crossing 40°C in April itself, with the India Meteorological Department issuing repeated heatwave alerts in multiple states this season. And summer has barely begun.

Now, a new IIT Bombay study from the Centre of Studies in Resources Engineering and the Centre for Climate Studies may explain why these brutal heat spells are becoming so common and so dangerous.

For years, many believed North India’s heatwaves were mainly caused by hot air blowing in from other regions. But researchers at IIT Bombay say that story is incomplete.

Their findings show many heatwaves over the Indo-Gangetic Plains are heavily shaped by what is happening locally: the land, moisture levels, clouds, soil and air right above us.

That matters because this belt is home to nearly 60 crore people.

WHY THIS STUDY MATTERS TO EVERYDAY PEOPLE

If heatwaves are caused only by distant weather systems, there is little a city can do except wait. But if local conditions help trigger them, forecasts can become sharper, faster and more specific.

That could mean warnings not just for North India, but for your district, your city, even your neighbourhood cluster.

Lead author Manali Saha, a PhD scholar at IIT Bombay, said forecasting has often focused on whether hot air is arriving from the northwest.

Their results suggest tracking local land and atmospheric signals may be more useful in predicting where heatwaves will form.

THE TWO TYPES OF HEAT THAT CAN HIT YOU

The study found that not all heatwaves feel the same because they are not the same.

Moist heatwaves:

These happen when pre-monsoon showers add moisture to the ground. That moisture later increases humidity and cloud activity. Nights stay hotter because clouds trap heat.

This is the kind of heat where sweating stops helping much. Your body struggles to cool itself. It feels sticky, suffocating and exhausting.

Dry heatwaves:

These form where soils are dry and skies stay clear. Sunlight keeps heating the ground, pushing temperatures even higher.

This is the classic scorching loo-type heat many North Indians know well. It often spreads wider and can last longer.

Researchers say both can be deadly, just in different ways.

WHY INDIA FEELS HOTTER EARLIER NOW

The study analysed 10 major pre-monsoon heatwave events since 2010. It found that once a large high-pressure system forms, local surface heating and sinking warm air can rapidly intensify temperatures.

That helps explain why heat now seems to arrive sooner, stay longer and feel harsher.

Climate change is also loading the dice. Background warming means local triggers can push temperatures into dangerous zones faster than before.

WHAT COULD CHANGE NEXT

Right now, many warning systems rely mainly on temperature thresholds. But IIT Bombay researchers say future alerts should also monitor:

• humidity near the surface
• dry air aloft
• soil moisture
• pre-monsoon rain patterns
• night cloud cover
• land heating trends

The team says it hopes to build a machine-learning-based decision-support system for better location-specific forecasts.

WHAT YOU SHOULD TAKE FROM THIS

India’s heat is no longer just a seasonal inconvenience. It is a health emergency, a work emergency and an education emergency for students sitting exams in extreme temperatures.

This research sends a clear message: heatwaves are not only coming from somewhere else. They are also building around us, from the ground up.

And if we understand that better, we may finally get smarter warnings before the next brutal spell hits.

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