The fog flight delays India sees every winter follow a calendar you can plan around. India's aviation regulator, the DGCA, set 10 December 2025 to 10 February 2026 as last winter's official fog window. Inside it, the dense fog at Delhi sits mostly in January and December, on the northern plains it tends to form in the early morning, and when it lifts, arrivals come back before departures do. Knowing those three things lets you pick a flight time, a buffer and a pickup plan before the season starts, instead of on the morning it goes wrong.
This guide is the calendar only; the landing technology itself, CAT III, is a separate subject.
The fog window on the calendar
The fog window is the official low-visibility period the DGCA declares for the winter, during which it holds airlines to low-visibility rules. For the 2025-26 season the regulator declared 10 December to 10 February, and airlines were required to roster pilots trained for low-visibility operations and to place CAT III B certified aircraft at fog-prone airports (Travel Trade Journal, 9 December 2025, captured 2026-09-27; The Tribune, 2 January 2026, captured 2026-09-27).
- Check this winter's dates. Treat 10 December to 10 February as the shape of the season, and check the current season's notice before you book a trip that falls near either edge.
- The fog behind it is northern. Delhi is the airport most people mean, and Lucknow, Amritsar and Jaipur are among the six Indian airports Business Today listed with CAT III capability as of December 2025, alongside Delhi, Bengaluru and Kolkata (Business Today, 18 December 2025, captured 2026-09-27). Even a trip that never touches the north can feel the window if the aircraft flying it spent the morning there.
Which months carry the dense fog
The best public picture of how fog is spread across the season comes from the meteorologists who observe it at Delhi's airport. A study by the India Meteorological Department's Meteorological Watch Office at IGI Airport counted fog days in the half-hourly airport weather reports across twelve winters, 2010-11 to 2021-22 (Kumar et al., Journal of Geomatics, April 2024, captured 2026-09-27). Its categories follow aviation practice: dense fog is visibility of 51 to 200 metres, very dense fog is below 50 metres.
| Month | Dense fog days, 12 winters | Very dense fog days, 12 winters | All-fog hours, 12 winters |
|---|---|---|---|
| November | 29 | 14 | 2,165.5 |
| December | 102 | 57 | 3,191 |
| January | 182 | 98 | 3,669.5 |
| February | 69 | 36 | 1,396 |
Read as a calendar, that gives you three bands:
- January is the core. It had the most dense and very dense fog days and the most fog hours of any month in the study.
- December is the build-up. December had a little over half of January's dense fog days, but still sits well above November and February on every measure in the table.
- February is the tail, not the all-clear. February had the fewest fog hours overall, yet the study found more dense and very dense fog days in February than in November. A trip in the first ten days of February is still inside the window for a reason.
Seasons vary: 2016-17 logged 253 fog days of all types and 2021-22 only 111, with fewer fog days in general after 2016-17 (Kumar et al., April 2024, captured 2026-09-27). One quiet winter does not promise another.
Which hours of the day
The hours matter as much as the month. The same paper summarises an earlier airport study from the north Indian plains. At Patna, over 2000 to 2010, fog mostly formed between 0000 and 0200 UTC, which is 5:30 to 7:30 in the morning in India, and dissipated between 0200 and 0500 UTC, which is 7:30 to 10:30 in the morning (Kumar et al., April 2024, citing Laskar et al., captured 2026-09-27). Treat these hours as a guide for the northern plains, not as a Delhi timetable.
In planning terms: a departure scheduled for the first bank of the morning at a northern airport is the most exposed slot of the day in December and January. A flight scheduled after the late morning usually starts in better visibility, although it can still inherit a delay from an aircraft that was held earlier.
Why arrivals come back before departures
On a bad fog morning the arrivals board and the departures board do not recover together, and the gap has a simple cause: landing and take-off have different visibility floors. Business Today, reporting on Indian operations, put the requirement at 75 metres of runway visual range for a CAT III(B) landing and 125 metres for take-off (Business Today, 18 December 2025, captured 2026-09-27).
As the fog thins in the late morning, visibility crosses the landing floor before it crosses the take-off floor. So the first thing that comes back is aircraft landing. Departures wait for more visibility, and then face three more hurdles:
- They need aircraft on the ground. A morning departure often uses an aircraft that was meant to arrive earlier. If that aircraft was held, diverted or cancelled, the departure has nothing to fly until it arrives.
- They move slower on the ground. The same Business Today report notes that the landing system helps an aircraft land but does not help it taxi in fog, and that Delhi's normal rate of about one movement a minute stretches to about one every three minutes in fog. The backlog clears at that slower pace.
- Cancellations come in pairs. On 30 December 2025, 60 arrivals and 58 departures were cancelled at Delhi, with 16 Delhi-bound flights diverted (DD News, 30 December 2025, captured 2026-09-27). On 2 January 2026, 66 flights were cancelled, 32 arrivals and 34 departures (The Tribune, 2 January 2026, captured 2026-09-27). The near-even split is what you would expect when an aircraft that does not arrive cannot operate its next departure either.
So a morning arrival can land while the departures board still looks frozen, and a departure delay can outlast the fog you can see from the terminal.
Planning around the window
- Move the morning, not the month. If you must fly from Delhi or another northern airport between mid-December and the end of January, a late-morning or afternoon departure avoids the hours in which fog most often forms. The Delhi to Mumbai route is a typical trip to plan this way.
- Give connections room. A connection through a northern airport in January needs more slack than the minimum. The departure leg is the one that recovers last.
- Check the evening before. A DGCA fog-season procedure lets airlines cancel, sufficiently in advance, flights they expect to run more than three hours late, and asks them to send delay information by SMS, WhatsApp and email (Business Today, 15 January 2024, captured 2026-09-27). Make sure the airline has your current phone number and email, and look for a message the night before an early flight.
- Read the airline's own policy for changes. What an airline offers when a fog-season flight is changed or cancelled is set out in its own published terms, and it differs by airline. Check that page, not 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, with gate and status alerts, so a fog morning shows up as a change on your flight rather than a surprise at the terminal. Our live flight tracking page describes that planned feature, and the Delhi airport page is the place to start in the directory for the airport this calendar is built around.
Questions people ask
When is fog season for flights in India? For planning, treat it as the DGCA's fog window, which ran from 10 December 2025 to 10 February 2026 last winter. Delhi's airport weather records show January with the most dense fog, then December, then February.
What time of day is fog worst at north Indian airports? The early morning. A study of Patna airport records found fog mostly forming between 5:30 and 7:30 in the morning India time and usually clearing between 7:30 and 10:30.
Why do departures stay delayed after arrivals start landing? Take-off needs more visibility than a low-visibility landing, 125 metres against 75, and departures often wait for aircraft held or diverted during the fog.
Is February safe to fly in north India? Safer than January, not fog-free. Delhi's twelve-winter study found fewer fog hours in February than in any other winter month, but more dense fog days than November.
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," 2 January 2026, https://www.tribuneindia.com/news/delhi/delhi-airport-sees-cancellation-of-66-flights-due-to-fog-and-low-visibility/amp, captured 2026-09-27
- DD News, "Dense fog: 60 arrival, 58 departure flights cancelled at Delhi airport," 30 December 2025, https://ddnews.gov.in/en/dense-fog-60-arrival-58-departure-flights-cancelled-at-delhi-airport/, captured 2026-09-27
- Business Today, "Explained: Why even CAT III compliant flights get hit by low visibility during fog," 18 December 2025, https://www.businesstoday.in/india/story/explained-why-even-cat-iii-compliant-flights-get-hit-by-low-visibility-during-fog-507230-2025-12-18, captured 2026-09-27
- Business Today, "DGCA issues SOPs for airlines amid flight delays, cancellations due to fog," 15 January 2024, https://www.businesstoday.in/india/story/share-real-time-information-dgca-issues-sops-for-airlines-amid-flight-delays-cancellations-due-to-fog-413367-2024-01-15, captured 2026-09-27, cited for the advance-cancellation procedure, which depends on the airline's own forecast of the delay
- Saurabh Kumar, S. H. Arun, S. Charan, J. Sebin and Rakesh Kumar, "Fog characteristics study over the IGI Airport, New Delhi during the winter seasons 2010-2022," Journal of Geomatics, vol. 18, no. 1, April 2024, https://pdfs.semanticscholar.org/e44c/cd5d909acdbe6b2753d62d238b2c7029a5fa.pdf, captured 2026-09-27
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