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Explained: Why Delhi had its wettest October day in four years

Why is it raining in Delhi in late October? A western disturbance brought 61.4 mm in a day and cleaner air. Here is what caused it and when it will end.

The Indian Idiot Desk

Explained2 min read5 sources
Scooters and a bicycle parked on a wet pavement in heavy rain at night in Connaught Place, New Delhi.
Photograph. · File photo: rain at night in Connaught Place, New Delhi, September 2007. · Credit: Vyacheslav Argenberg / Wikimedia Commons · Image source · License: CC BY 4.0 · Changes: Cropped to a 3:2 frame and resized to 1200 × 800 pixels; JPEG recompressed. No other visual changes.

What happened? Delhi’s Safdarjung observatory recorded 61.4 mm of rain in the 24 hours ending 8.30 am on Friday (30 October), the city’s wettest October day since 9 October 2022, when it got 74 mm, The Indian Express reported. Delhi has now had 123.3 mm of rain this October against a normal of 15.1 mm for the whole month.

Why is it raining in Delhi now? The India Meteorological Department (IMD) said an active western disturbance was the main reason. Western disturbances are eastward-moving weather systems that originate in the Mediterranean region and nearby areas.

Is this Cyclone Arnab? Not directly. The remnant of Cyclone Arnab, which hit the Andhra Pradesh coast this week and flooded parts of Odisha, has been affecting parts of central and eastern India, as The Indian Idiot reported, while the western disturbance drove the rain over northwest India, including Delhi, according to IMD officials.

Is October rain unusual? Yes, October is normally one of Delhi’s driest months. There was little or no rain in October between 2017 and 2020, while October 2021 got 122.5 mm, October 2022 got 128 mm and October 2025 got 89.3 mm.

Why did it feel so cold? The clouds and rain kept the day cool. On Thursday the maximum temperature at Safdarjung fell to 25.4°C, 5.6 degrees below normal and the coldest October day in four years.

What did it do to the air? The rain washed out pollutants. The air quality index fell from 222 (poor) on Thursday afternoon to 90 (satisfactory) on Friday morning, according to Central Pollution Control Board data.

Will it keep raining? The IMD issued a short red alert for rain, thunderstorms and strong winds on Friday morning, with a yellow alert covering the rest of the day. Skies are expected to stay partly cloudy on Saturday and turn mainly clear from Sunday.

More to read

Behind the story

Read the sources and explore the context for yourself.

  1. The Indian Express: Delhi's air turns 'satisfactory' after record October rain in 4 years (30 Oct 2026)indianexpress.com
  2. The Hindu: More showers expected in Delhi after overnight rain; wettest October day in four years (30 Oct 2026)thehindu.com
  3. Hindustan Times: Delhi braces for another wet day, red alert on for rain and thunderstorms (30 Oct 2026)hindustantimes.com
  4. India Today: Delhi records coldest October day in four years (29 Oct 2026)indiatoday.in
  5. The Indian Idiot: Cyclone Arnab aftermath: Coast Guard airlifts stranded people as floods cut off 70 villages in Odisha’s Ganjam (29 Oct 2026)theindianidiot.com
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