Cyclone Ditwah: What this storm is trying to tell us?

Cyclone Ditwah changed the weather and sparked a few questions.

It is 12 noon on Dec 3, 2025. At this hour of the day, I will usually be sweating a lot, sitting in my office space at home, because that room gets hot easily with not much ventilation. My water bottle and hand towel often come to my rescue.

However, today and for the past couple of days it has been the other way around. It is cold. Sometimes freezing cold.

Yes, it is December. But it is Chennai.

As I was growing up, I have seen and experienced only three weathers (mostly): hot, hotter, and hottest. Of course, rains and winters will be there but hot days stays vividly in my memory.

But these days, things are different. I am wearing a jerkin inside the house—something completely unlike me or anyone living in Chennai.

This time, it is Cyclone Ditwah that is doing the damage. According to TN SMART – TN system for multi-hazard potential impact assessment, two regions in Chennai (Manali new town & Ennore) has received more than 204 mm i.e. extreme heavy rain and four regions between 115 to 204 mm rainfall i.e. very heavy rainfall. And before reaching us, Ditwah had already done enough damage to Sri Lanka as well. According to International Organisation for Migration, 25 districts in Srilanka has been flooded with 150-500 mm of continuous very heavy rainfall between Nov 28 – 30, 2025. The island nation has declared a state of emergency as severe flooding, landslides, and damage to infrastructure have affected nearly 1 million people and displaced over 209,000 individuals. 

Whoa! That’s huge. This made me wonder – Usually, a cyclone weakens after making landfall.

Why didn’t that happen this time?

I started reading about Ditwah – its journey, its strange behaviour, and the science behind why it refused to weaken and why Chennai ended up receiving so much rain.

The more I understood, the more I realised: this wasn’t just a weather event. Ditwah was trying to tell us something.

So here’s what I found.

Cyclone Ditwah began forming near Sri Lanka, barely 90 kilometres away from its coastline—far closer than usual for a cyclone. The water in the Bay of Bengal was warm, around 28–30°C, which is like a warm bath for cyclone formation. Warm water evaporates faster, the moist air rises, the Earth’s spin twists it, and a spiral begins to form. That’s how most cyclones are born.

By November 27, this small disturbance in the southwest Bay of Bengal had grown into a full cyclonic storm. It was named “Ditwah,” after a lagoon in Yemen.

But the real surprise came after.

Usually, when a cyclone hits land, it weakens rapidly. Land cuts off its fuel source which is warm ocean water. Land also creates friction with trees, buildings, and mountains, which slows down the spinning winds. In short, a cyclone over land is a cyclone running out of battery.

Ditwah didn’t follow this rule.

Instead of crashing directly onto Sri Lanka and weakening, it travelled parallel to the coastline. One half of the cyclone remained over the land, but the other half stayed over the warm Bay of Bengal, continuously charging itself. This unique “half-land, half-sea” position allowed Ditwah to stay alive.

And that made it far more dangerous.

Sri Lanka received unbelievable amounts of rainfall. In some places, 400 mm fell in just 24 hours. Hillsides collapsed. Villages were buried under landslides. Rivers overflowed.

Then Ditwah took its turn over the Bay of Bengal.

You would expect it to weaken at least now as it spent so much time on land, but Ditwah has other plans. As soon as it touched warm water again, its strength doubled. Forecasters issued red alerts for Tamil Nadu, Puducherry, and Andhra Pradesh. Chennai braced itself.

Instead of making landfall in Tamil Nadu, it began moving parallel to our coast as well—sometimes just 30 kilometres offshore. It kept raining, and raining, and raining. And because the system was moving very slowly, at just 3–5 km/h (slower than how fast we walk), the same patches of land received rain continuously.

That’s why Chennai was flooded even though Ditwah never technically “hit” us.

Chennai received more rainfall – around 700 mm between Dec 1 to 4, 2025 according to Regional Meteorogical Centre, Chennai – because the cyclone stayed close enough to keep feeding clouds over the same region, hour after hour. It was getting constant moisture from the sea, and we were getting constant rain from the sky.

Science taught us that, storms weaken quickly after landfall. It taught us well. No doubt. But did Ditwah ever made the landfall? That’s the question. It was always half over the ocean. And the ocean was warm enough to feed this fella to be stay energetic for a week now.

That brings us to the bigger question: Why was the Bay of Bengal so warm? And why are storms like Ditwah becoming common?

The Bay of Bengal is warming faster than many parts of the world – it has increased from 0.5 to 1 degree over the last 50 years, says scientists from Indian Institute of Tropical Meteorology, Pune. What does it mean?

Warm water = more evaporation = more moisture = more energy
And more energy = stronger, longer-lasting storms

This is why Ditwah intensified quickly, and why it didn’t weaken.

Scientists have been warning us for years that warmer oceans will lead to cyclones that behave unusually.

The Bay of Bengal also has a natural setup that supports strong cyclones. Huge rivers like the Ganga and Brahmaputra pour freshwater into it. Freshwater traps heat more easily than saltwater. So, the top layer of the ocean remains warm, like a lid on a pot. That warm layer keeps feeding cyclones.

So, what is Ditwah telling us?

The climate is changing faster than expected. Interestingly, cyclones are learning new tricks. And its shouldn’t be surprising as we have been warned about this. Quite a lot, actually.

Once again, Climate Change is not something that we are going to face in future. Its here! We are experiencing it. And our children are going to suffer, if we don’t know push the governments to act fast, before passing the point of no return.

We have passed the level, when individual actions yielded results. Its time for our systems / Governments to act.

p.s. as I complete this draft on Dec 4, it was around 3 pm and its still cold. Of course, the rainfall has come down but not the cold wind.