Planning around flight delays India season by season is less about one bad month and more about knowing which part of the country the weather is working on at the time. Fog sits over the north in winter. Afternoon storms hit the east before the monsoon. The southwest monsoon then walks up the country from Kerala, and when it leaves, a second monsoon and the main cyclone season arrive in the south and east. This page maps the whole year and points to the detailed guide for each season.
The Indian year at a glance
| Months | Main weather driver | Where it bites hardest | Read next |
|---|---|---|---|
| December to February | Dense fog | Delhi and the northern plains | our fog-season guide; Delhi airport |
| March to May | Nor'wester storms, first cyclone season | Kolkata, Guwahati, the east and north-east; thunderstorms in the north | Kolkata airport, Guwahati airport |
| June to September | Southwest monsoon | Mumbai and the west coast first, then the whole country | our monsoon calendar; the Mumbai monsoon runway story |
| October to December | Northeast monsoon, main cyclone season | Chennai, Tamil Nadu, coastal Andhra Pradesh, the Bay of Bengal coast | Chennai airport, Bengaluru airport |
These are tendencies, not timetables, and a delay in one city travels. An aircraft held on the ground in fog-bound Delhi can be the same aircraft that was supposed to operate a later sector somewhere sunny, which is why the Mumbai to Delhi route can feel a northern winter even when Mumbai itself is clear.
December to February: fog across the north
India's aviation regulator, the DGCA, declared 10 December 2025 to 10 February 2026 as the official fog window for last winter, and airlines prepare for it by rostering crews trained for low-visibility landings and placing aircraft certified for CAT III B operations at the airports most prone to fog (Travel Trade Journal, 9 December 2025, captured 2026-09-27).
Even with that preparation, a bad fog day still thins the schedule. On 2 January 2026, airlines cancelled 66 flights to and from Delhi because of fog and reduced visibility, 32 arrivals and 34 departures (The Tribune, captured 2026-09-27). If you are flying through the north in these weeks, the dedicated fog-season guide in this series covers the fog window in detail.
March to May: afternoon storms and the first cyclones
The months between fog and monsoon are not quiet. In the east and north-east, this is the season of the nor'wester, called Kalbaisakhi in Bengal: a short, violent thunderstorm with gale-force wind, heavy rain and sometimes hail, which usually builds in the afternoon or just before sunset. It generally runs from April until the monsoon sets in, with the odd March storm (Wikipedia, "Nor'westers", captured 2026-09-27).
On 31 March 2024, a storm at Guwahati blew away part of the forecourt roof and drove visibility down so fast that six flights were diverted to Agartala and Kolkata (The Tribune, captured 2026-09-27). The north gets its own version: on 30 May 2022, a Monday afternoon thunderstorm in Delhi led to at least five diversions and 70 delayed flights (The Tribune, captured 2026-09-27).
This is also the first of India's two cyclone seasons. Research on the North Indian Ocean describes cyclone activity peaking twice a year, once in the pre-monsoon months of April to June and again, more often, from October to December (Frontiers in Earth Science, 2022, captured 2026-09-27). A pre-monsoon cyclone can shut an airport outright: when Cyclone Remal approached in May 2024, Kolkata suspended flight operations for 21 hours from Sunday noon, and eight Kolkata-bound flights were diverted to Guwahati, Gaya, Varanasi and Bhubaneswar (The Tribune, 27 May 2024, captured 2026-09-27).
June to September: the southwest monsoon moves north
The southwest monsoon normally sets in over Kerala around 1 June and then advances north in surges (India Meteorological Department, captured 2026-09-27). The normal date for it to cover the whole country is 8 July, and in 2026 it reached the last parts of Rajasthan, Haryana and Punjab on 9 July (DT Next, 9 July 2026, captured 2026-09-27). It then retreats, normally starting from north-west India around 17 September and leaving the country completely by 15 October (The Tribune, 12 September 2025, captured 2026-09-27).
So "monsoon delays" do not hit everywhere at once. The west coast gets it early, and Mumbai is the familiar case: on 21 July 2024, heavy rain led to 36 cancellations at Mumbai airport, and runway operations were suspended twice within about an hour (News On AIR, 22 July 2024, captured 2026-09-27). Why one city's rain spreads so far is the subject of our Mumbai monsoon piece on the single-runway problem.
For the region-by-region onset and peak dates, read the monsoon calendar guide in this series.
October to December: the northeast monsoon and the second cyclone season
As the southwest monsoon leaves the north, the south-east gets its main rains. The India Meteorological Department's Chennai office treats October to December as the northeast monsoon season for five subdivisions: Tamil Nadu with Puducherry and Karaikal, Coastal Andhra Pradesh and Yanam, Rayalaseema, South Interior Karnataka and Kerala. In 2025 it set in on 16 October, against a normal date of 20 October (IMD Chennai, Report on Northeast Monsoon 2025, captured 2026-09-27).
So the "worst month to fly India" question has a regional answer. A Delhi traveller's hardest stretch falls inside the December to February fog window. A Chennai traveller's is more likely October to December, when the northeast monsoon and the post-monsoon cyclone peak overlap over the Bay of Bengal (Frontiers in Earth Science, 2022, captured 2026-09-27). Chennai airport and the east-coast airports feel that season first; Bengaluru sits inside the South Interior Karnataka subdivision the IMD tracks for the same season.
Crowding is a separate question from weather. How busy Indian airports get across the year, festive months included, is the subject of the companion guide to Indian air traffic by season in this series.
Using the calendar when you book
Four habits follow from the map:
- Match the time of day to the season. Nor'westers in the east usually build in the afternoon or just before sunset, so a morning flight in April or May sidesteps the usual storm window. In the northern fog window, keep the day flexible rather than stacking a meeting on landing time.
- Leave room on connections in the risky quarter for that city. A connection that is fine in April through Delhi may be thin in January, and one that is fine in January through Kolkata may be thin in May.
- Watch the inbound aircraft, not only your own flight. A clear sky at your airport does not help if the aircraft is still on the ground in fog or rain somewhere else.
- Read the airline's own policy before you travel. What happens to your booking after a weather delay or cancellation is set by the airline's published terms. Check them on the airline's own site rather than relying on a general guide.
How TrackMyWings helps
TrackMyWings™ is a live flight-tracking platform in development, India-first in its go-to-market. A private Android beta has been running on the Play internal testing track since 24 August 2026, and public launch has no fixed date. When it launches, the planned job is the one this calendar points at: following your flight and the aircraft behind it, with gate and status alerts, so a weather season shows up as a change on your flight rather than a surprise at the airport.
Questions people ask
What is the worst month to fly in India? It depends on where. For Delhi and the northern plains, the risk sits in the December to February fog window. For Mumbai and the west coast, it is the southwest monsoon months from June to September. For Chennai and the east coast, it is October to December. There is no single month that is bad everywhere.
Is monsoon season bad for flights across all of India? Not at the same time. The southwest monsoon starts over Kerala around 1 June and normally covers the whole country only by early July, so the west coast feels it weeks before the north does.
Does India have a cyclone season? Two of them. Cyclone activity over the Bay of Bengal and Arabian Sea peaks in April to June and again, more often, in October to December.
Are the months between fog and monsoon safe to fly? Not everywhere. March to May brings short, strong afternoon storms to the east and north-east, and occasional thunderstorms to Delhi.
Sources
- Travel Trade Journal, "Air India activates fog-season plan as DGCA sets Dec 10 to Feb 10 low-visibility window," 9 December 2025, https://traveltradejournal.com/air-india-activates-fog-season-plan-as-dgca-sets-dec-10-feb-10-low-visibility-window/, captured 2026-09-27
- The Tribune, "Delhi airport sees cancellation of 66 flights due to fog and low visibility," https://www.tribuneindia.com/news/delhi/delhi-airport-sees-cancellation-of-66-flights-due-to-fog-and-low-visibility/amp, captured 2026-09-27
- Wikipedia, "Nor'westers," https://en.wikipedia.org/wiki/Kalbaisakhi, captured 2026-09-27
- The Tribune, "Sudden rain, storm damage Guwahati airport; several flights diverted," https://www.tribuneindia.com/news/india/sudden-rain-storm-damage-guwahati-airport-several-flights-diverted-605985, captured 2026-09-27
- The Tribune, "5 flights diverted, 70 delayed at Delhi airport due to thunderstorm," https://www.tribuneindia.com/news/delhi/5-flights-diverted-70-delayed-at-delhi-airport-due-to-thunderstorm-399562, captured 2026-09-27
- Frontiers in Earth Science, "The appraisal of tropical cyclones in the North Indian Ocean," 2022, https://www.frontiersin.org/journals/earth-science/articles/10.3389/feart.2022.823090/full, captured 2026-09-27
- The Tribune, "Cyclone Remal: 8 Kolkata-bound flights diverted to other cities due to bad weather," 27 May 2024, https://www.tribuneindia.com/news/india/cyclone-remal-8-kolkata-bound-flights-diverted-to-other-cities-due-to-bad-weather-625349, captured 2026-09-27
- India Meteorological Department, "Onset and Advance of Monsoon," https://mausam.imd.gov.in/imd_latest/contents/onset.php, captured 2026-09-27
- DT Next, "Southwest monsoon covers entire country: IMD," 9 July 2026, https://www.dtnext.in/news/national/southwest-monsoon-covers-entire-country-imd, captured 2026-09-27
- The Tribune, "Monsoon withdrawal likely to begin around September 15: IMD," 12 September 2025, https://www.tribuneindia.com/news/india/monsoon-withdrawal-likely-to-begin-around-september-15-imd, captured 2026-09-27
- News On AIR, "36 flights cancelled at Mumbai airport due to heavy rains," 22 July 2024, https://www.newsonair.gov.in/36-flights-cancelled-at-mumbai-airport-due-to-heavy-rains, captured 2026-09-27
- India Meteorological Department, Regional Meteorological Centre Chennai, "Report on Northeast Monsoon 2025," https://mausam.imd.gov.in/chennai/mcdata/ne_monsoon_2025.pdf, captured 2026-09-27
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