Cyclone Ditwah brings heavy rain to Chennai; IMD issues orange and red alerts: What to know

Chennai: Chennai and its suburbs were hit by an intense spell of rain on Monday morning after Cyclone Ditwah, which had weakened into a deep depression over the Bay of Bengal, regained moisture overnight. The unexpected deluge flooded low-lying neighbourhoods, slowed traffic across the city and forced authorities to shut schools and colleges.

The India Meteorological Department restored the orange alert for Chennai and issued a red alert for Tiruvallur around 10am as steady rain persisted from early morning. Residents woke to one of the wettest days of the season, with cloud cover thickening as the system drifted slowly northward at about 5km/h, staying close to the Tamil Nadu coast.

Between 8.30am and 7.30pm, Chennai recorded 10cm of rain, categorised as “moderate”, though several northern pockets saw higher totals. Nungambakkam registered 9.45cm, Meenambakkam 6.2cm, while Ennore reported 13cm between 8.30am and 2pm. Parry’s Corner, Ice House, Madhavaram, Saligramam and Vadapalani also surpassed 10cm.

The IMD had downgraded alerts for Chennai and Tiruvallur on Sunday evening after the cyclone appeared to weaken. However, the system regained strength overnight, drawing in moisture as it remained 30km–40km offshore, leading to renewed warnings of heavy rain for Chennai, Tiruvallur, Kancheepuram and Chengalpet on Tuesday.

Cyclone Ditwah’s projected path remained uncertain. The IMD forecast that the system would weaken into a depression and cross the coast near Nellore early on Tuesday. Independent forecasters, however, predicted scattered bursts across Chennai and surrounding districts. Weather blogger Pradeep John said the clouds would continue to build as long as the system stayed near the coast, adding that the depression was likely to remain close to Chennai for the next 36 hours. If the westerly trough moved away by Wednesday, the system could drift westward into Tamil Nadu or towards the south Andhra Pradesh coast as a weakened cyclone.

Cyclone Ditwah, after losing strength over the Bay of Bengal on Sunday, unexpectedly intensified overnight and delivered the season’s wettest morning for Chennai on Monday. The city saw continuous rainfall from around 5am as the system, lingering close to the coastline, thickened its cloud cover and pulled in moisture.

What began as a relatively calm Sunday evening turned into persistent showers by dawn, catching many residents off guard. Several parts of north Chennai and neighbouring districts experienced heavy downpours that inundated roads and residential settlements. Commuters, including schoolchildren, were forced to wade through waterlogged streets as traffic slowed to a crawl.

By 10am, the India Meteorological Department reinstated its orange alert for Chennai, signalling very heavy rain, while Tiruvallur was placed under a red alert for extremely heavy rainfall. Data from the day showed notable variation across the city: Chennai’s overall rainfall between 8.30am and 7.30pm stood at 10cm, but specific localities recorded considerably higher numbers. Ennore topped the Greater Chennai Corporation’s charts with 13cm in under six hours, while Parry’s Corner, Ice House, Madhavaram, Saligramam and Vadapalani all exceeded 10cm.

Earlier on Sunday, IMD had downgraded alerts to yellow for Chennai and orange for Tiruvallur, expecting the cyclone to weaken. However, the system’s overnight resurgence altered the forecast. Meteorologists now expect Cyclone Ditwah to hover 30km–40km off the coast and bring more heavy rain to Chennai, Chengalpet, Kancheepuram and Tiruvallur on Tuesday.

The cyclone’s track continues to divide forecasters. IMD’s official projection suggests the system will weaken into a depression and make landfall near Nellore early Tuesday. Independent weather observers disagree, anticipating scattered but intense bursts across Chennai and adjacent districts as long as the cyclone remains nearshore. Weather blogger Pradeep John noted that clouds would continue to rebuild over the region while the system is positioned close to the coast. He added that the depression might remain stalled near Chennai for up to 36 hours and could later move inland towards Tamil Nadu or the south Andhra Pradesh coast if the westerly trough influencing it shifts on Wednesday.

This combination of uncertainty in trajectory and high moisture availability is expected to keep Chennai on alert, with authorities monitoring rain intensity and local flooding as the system continues to linger offshore.