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The calendar says autumn. The thermometers across large parts of India say otherwise. In the first week of October, cities that should be easing into festive-season evenings were posting the kind of numbers more familiar in late April, and the weather office expects much of the month to stay that way.
This explainer looks at where the heat is showing up, why October has turned into a second summer this year, and why the nights may matter even more than the days.
A second summer, from Rajasthan to the Konkan coast
In the north, Delhi was expected to touch about 36°C on 6 October, while Pilani in Rajasthan could reach 40°C. Even Kashmir, where October is usually about crisp air and turning chinar leaves, was running warm: Srinagar was forecast at 30.8°C and Kathua in Jammu at 34.2°C.
Maharashtra has been hit harder. On 4 October, Malegaon recorded 38.4°C, Amravati 38°C, Dahanu 37.9°C and Ratnagiri 37.7°C, with Mumbai at 36.5°C. Malegaon’s reading was 5.9°C above normal, and Pune’s Lohegaon station was 4.1°C above its usual mark. In Mumbai, the discomfort is as much about moisture as temperature: days after the monsoon left, the city was still hot and humid, with a morning minimum of 28°C.
The south is not exempt. IMD’s daily bulletin for 3 October showed maximum temperatures appreciably above normal at many places over Coastal Karnataka, and minimum temperatures appreciably above normal at a few places in Punjab and West Rajasthan. The pattern spans the country rather than a single region.
What IMD expects for the rest of October
IMD’s monthly outlook, issued on 30 September, offers little relief. Rainfall over the country as a whole is likely to be below normal in October, under 85% of the long period average, and above-normal daytime temperatures are expected over most of the country. Night temperatures are also likely to run above normal almost everywhere, with most of Northeast India the main exception.
There is some short-term respite. Isolated to scattered rain was forecast over Delhi, Haryana and Punjab between 6 and 11 October, along with wetter spells over Kerala, coastal Karnataka and Tamil Nadu. A few rainy days can take the edge off, but they do not change the month’s overall direction.
Why October gets hot in the first place
Some October heat is entirely normal. Once the monsoon withdraws, the thick cloud cover that shaded the land for months clears out, and the sun, still fairly high in the sky over most of India, beats down on the ground with little to block it. At the same time, soils and the air above them hold on to monsoon moisture, so the heat arrives with humidity attached. Coastal cities feel this most sharply. IMD’s Mumbai office has described a spike in heat after the monsoon’s withdrawal as typical for the city, which is why ‘October heat’ is a familiar phrase in Mumbai and along the Konkan.
What is different this year is how early, how widespread and how intense the spell has been. Three factors are working together.
A weak, dry exit: The monsoon did not leave with a final burst of rain this year; it faded out. Weather experts in Maharashtra say this year’s October heat arrived roughly 15 days earlier than usual, because the retreating monsoon was weak and left behind dry, clear skies. Delhi saw the monsoon off on 23 September, two days ahead of its normal date.
Large parts of western India also ended the season short of water. Gujarat finished with about 89% of its normal rainfall, but Kutch received only 57.6%, with North Gujarat and Saurashtra near 71%. Drier soil heats up faster, because less of the sun’s energy goes into evaporating water and more goes into warming the ground and the air above it.
A powerful El Niño: The bigger driver sits thousands of kilometres away in the Pacific. IMD says strong El Niño conditions are currently prevailing over the equatorial Pacific, and models indicate the event will keep strengthening through the end of the year. El Niño tends to weaken monsoon circulation and leave India drier and warmer.
Its fingerprints were already visible in the summer. India recorded its hottest August since records began in 1901, with a mean temperature of 28.01°C, as August rainfall fell 16% below normal. Some global model runs suggest this could become one of the strongest events on record, with median projections above the 2015-16 peak, which would keep the warmth going into winter and early 2027. Projections like these carry real uncertainty, but the direction is consistent across forecasts.
El Niño has done this before. In 2023, another El Niño year, August, September and November each ranked as India’s warmest on record for those months.
A warmer baseline: Underneath the El Niño signal is a long-term rise in temperatures that makes every hot spell start from a higher floor. October is a clear example. In 2024, India recorded its warmest October since 1901, with a mean temperature of 26.92°C, 1.23°C above normal, and the highest October minimum temperatures on record. That was not an El Niño year. IMD linked part of that heat to the absence of active western disturbances, the weather systems that normally bring clouds and rain to north India in autumn.
Put the three together, a dry retreat, a strong El Niño and a warmer baseline, and a hot October stops being a surprise. It becomes the expected outcome.
The nights may matter more than the days
Daytime peaks make headlines, but the forecast for warm nights may be the more serious concern for health. Bodies recover from heat stress overnight; when nights stay warm and humid, that recovery does not happen.
This is already a trend. A CEEW analysis found that around 70% of Indian districts saw more than five additional very warm nights per summer over the last decade, compared with only about 28% that saw a similar rise in very hot days. Among the metros, Mumbai recorded 15 more very warm nights per summer, Bengaluru 11, Delhi 6 and Chennai 4.
Humid heat is also creeping beyond the traditional summer months. Research summarised by IIT Madras’s Shaastra magazine notes that the most dangerous form of humid heat stress currently affects about 1% of India between July and October, but could spread to more than half the country during the monsoon months at 2°C of warming.
Most of India’s heat governance has not caught up. A recent study found that Heat Action Plans and urban climate policies still focus mainly on daytime heatwaves, and the CEEW work found that many first-generation plans do not account for night-time heat, humidity or local vulnerabilities. Almost all of them are also built around the March to June season, which leaves an October heat spell largely outside their scope.
Who feels it most
The people most exposed are the ones who cannot step out of it: construction workers, street vendors, delivery riders, traffic police and farm labourers. October also brings large outdoor crowds for Navratri, Durga Puja and other festivals, often packed into pandals and processions late into warm, humid evenings.
For farmers, the heat lands at the start of the rabi sowing window. IMD warns that below-normal rain in the post-monsoon season could hurt soil moisture, raise irrigation needs and reduce reservoir and groundwater recharge. Warm soils and dry fields make it harder to establish wheat, gram and mustard crops on time.
What to watch next
IMD will issue its outlook for November towards the end of October, and that forecast will show whether the warmth is expected to carry into the winter months. For south peninsular India, the northeast monsoon could still bring meaningful rain, with IMD expecting normal rainfall over the region for October to December.
For the rest of the country, the lesson of this October is a simple one. The comfortable gap between the end of the monsoon and the start of winter is narrowing. Planning for heat, in hospitals, workplaces, schools and city budgets, can no longer stop at the end of June.
References
Maharashtra Faces Early ‘October Heat’; Malegaon Records 38.4°C, Temperatures Rise Across State
https://www.uniindia.com/west-india/weather-mumbai-heat-humidity-and-moderate-aqi/204544
https://mausam.imd.gov.in/backend/assets/aiwfb_pdf/e8e6319f59f254025ab997d468591e35.pdf
https://mausam.imd.gov.in/Forecast/marquee_data/Press_Release%20OND_30-09-2026.pdf
https://mausam.imd.gov.in/newdelhi/archive/2026-09-23/press_release_en.pdf
Southwest monsoon officially withdraws from entire Gujarat on October 3
https://www.khaleejtimes.com/asia/india-hottest-august-since-1901-average-temperature-28-degrees
https://theprint.in/environment/2026-el-nino-strongest-on-record/2986859
https://www.ceew.in/sites/default/files/ceew-how-extreme-heat-is-impacting-india-press-release.pdf
https://shaastramag.iitm.ac.in/special-feature/gathering-clouds
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