If you are planning around monsoon flight delays India-wide, the useful question is not "is it monsoon season?" but "has the monsoon reached the city I am flying from, or to, yet?" The India Meteorological Department (IMD) publishes a normal date for both. On those normals the southwest monsoon sets in over Kerala on 1 June, covers the whole country by 8 July, starts withdrawing from the far northwest in mid-September and leaves south India by 15 October. Then a second season, the northeast monsoon, arrives on the Tamil Nadu coast around 20 October. This guide lays that out month by month, city by city, with each city linked to its airport page and every date traced to IMD, retrieved on 2026-09-27.
A normal date is an average, not a forecast. In any given year the monsoon runs early or late, sometimes by a week or more. Treat the dates below as the shape of the season, and check IMD's own bulletins for the year you are flying in.
How IMD dates the monsoon
IMD revised its normal dates in 2020. The older set came from records at 149 stations over 1901 to 1940. The revised onset normals use data from 1961 to 2019, and the revised withdrawal normals use 1971 to 2019 (IMD, "New Normal Dates of Onset/Progress and Withdrawal of Southwest Monsoon over India," retrieved 2026-09-27). IMD said it would use the new dates from 1 June 2020.
Two changes matter most to anyone travelling north of the Deccan. Onset over Kerala stayed at 1 June, but the monsoon now reaches extreme northwest India on 8 July rather than 15 July. And withdrawal from northwest India now runs roughly 7 to 14 days later than the older dates, while the final withdrawal over south India stayed at 15 October (same IMD release).
One small trap: IMD's own onset explainer page still says the monsoon "covers the entire country around 15th July" (IMD, "Monsoon Information: Onset," retrieved 2026-09-27). That is the older normal. The 2020 release and its city table are the current reference, and that table is what this calendar uses.
Late May to early June: Kerala, the south and the northeast
The season opens in Kerala. IMD's normal onset over Kerala is 1 June, and Thiruvananthapuram's normal onset date in the city table is 1 June too. That puts Thiruvananthapuram and Kochi among the first airports on the Indian mainland to fly inside the monsoon each year.
Within the first week the rain moves up both coasts and into the northeast. The IMD table gives Chennai 4 June, Guwahati 4 June, Panjim in Goa 7 June and Hyderabad 8 June. So by the second weekend of June, on normal dates, flights through Chennai, Guwahati, Goa and Hyderabad are all operating in monsoon conditions.
Chennai is the odd one out. It gets a southwest monsoon onset date, but Tamil Nadu sits in a rain shadow during this season, and its main rains come later, from October (IMD Regional Meteorological Centre Chennai, "Report on Northeast Monsoon 2018," retrieved 2026-09-27). More on that below.
Mid-June: Mumbai, Kolkata and the central belt
The middle of June is when the monsoon reaches the two busiest coastal metros. IMD's new normal for Mumbai is 11 June, one day later than the older 10 June. Kolkata's is also 11 June. Inland, Pune's normal is 10 June and Nagpur's is 15 June.
For flyers, this is the week the calendar changes character at Mumbai and Kolkata. A trip booked for the first week of June and one booked for the third week can sit on opposite sides of the onset line, even though both are "June".
Late June to 8 July: the north and the northwest
The monsoon reaches the north last, and this is where the 2020 revision shifted the most dates. The IMD city table gives:
- Ahmedabad: 21 June
- Lucknow: 23 June
- Chandigarh: 26 June
- New Delhi: 27 June
- Jaipur: 1 July
- Jaisalmer: 8 July
Jaisalmer's 8 July is the same date IMD now gives for the monsoon covering the whole country. If you are flying to Rajasthan in the last week of June, you may be ahead of the rains; the same route in mid-July is inside them.
The peak: July and August
Once the monsoon has covered the country, on normal dates from 8 July, every region on this calendar is inside the season at the same time. IMD's Chennai centre describes the June to September southwest monsoon as India's chief rainy season (RMC Chennai report, retrieved 2026-09-27). Through July and August, every city in the table is past its onset date and none has reached its withdrawal date. The caveat is Tamil Nadu's coast, which sits in a rain shadow during this season.
For planning, that is the practical meaning of "peak" here: it is the window when a weather-related schedule change can come from the departure city, the arrival city or somewhere along the way, because all three are in the monsoon at once. It is not a claim that every day is wet, only that no region on the calendar is outside the season.
Withdrawal: 17 September to 15 October, northwest first
The monsoon leaves in roughly the reverse order it arrived. IMD does not attempt withdrawal from extreme northwest India before 1 September, and it declares withdrawal from the southern peninsula, and so from the whole country, only after 1 October (IMD withdrawal page, retrieved 2026-09-27).
Within that frame, the new normal withdrawal dates in the IMD table run:
- Jaisalmer: 17 September
- Jaipur and Chandigarh: 22 September
- New Delhi: 25 September
- Ahmedabad: 30 September
- Lucknow: 3 October
- Nagpur: 6 October
- Mumbai: 8 October
- Pune: 11 October
- Kolkata: 12 October
- Goa, Hyderabad and Guwahati: 14 October
The final withdrawal date over south India is 15 October. For people searching monsoon withdrawal 2026 dates specifically, the right place to look is IMD's daily withdrawal line for the current year; the list above is the normal against which each year's line is measured.
October to December: the northeast monsoon
After the southwest monsoon withdraws past about 15 degrees north, the low-level winds over the south reverse from southwesterly to northeasterly. IMD's Chennai centre puts the normal date for easterlies over southeast peninsular India at 14 October and the normal onset of the northeast monsoon over coastal Tamil Nadu and south coastal Andhra Pradesh at 20 October (RMC Chennai report, retrieved 2026-09-27).
The northeast monsoon is smaller than its southwest counterpart and covers five subdivisions: Tamil Nadu (with Puducherry), Kerala, Coastal Andhra Pradesh, Rayalaseema and South Interior Karnataka. For Tamil Nadu it is the chief rainy season of the year. The same report notes that October to December is also the primary cyclone season for the Bay of Bengal and the Arabian Sea.
That is why the IMD city table marks Chennai and Thiruvananthapuram with an asterisk instead of a withdrawal date: the southwest monsoon retreats and the northeast monsoon takes over. For flyers through Chennai the wet season on this calendar is October to December, not July. Kerala, including Kochi, sits in both seasons.
What the calendar means on travel day
Monsoon weather affects flights through a handful of specific hazards. When India's aviation regulator, the DGCA, revised its operating guidelines for adverse weather on 12 June 2025, it named heavy rainfall, turbulence, windshear, lightning, hailstorms and en route icing (Deccan Chronicle, "DGCA revises guidelines for monsoon flying," published 2025-06-24, retrieved 2026-09-27). The same guidelines urged airlines to put safety ahead of schedule and to treat air turnbacks and diversions as proactive safety measures rather than failures. They also flagged a night-rain illusion: wet runways reflect less light, which can make an aircraft seem farther from the runway than it is.
A diversion or hold on a monsoon evening is the system doing what the regulator asked. What that means for your ticket is a separate question. Rebooking, refunds and any compensation are set by the airline's own published policy and conditions of carriage, so check those directly with the airline rather than relying on a general guide.
A few habits follow from the calendar:
- Check which side of the onset line you are on. A Delhi trip on 20 June and one on 5 July can fall on opposite sides of the 27 June normal.
- Look at both ends. In mid-June Mumbai is usually inside the monsoon while Delhi is not; in mid-October Delhi is out and Chennai is about to begin.
- Watch the inbound aircraft. A weather hold at one airport can delay the aircraft due to fly your leg from another, even on a dry day where you are.
- Read IMD's forecast for the day, not only the normal. Normals set expectations; the daily bulletin tells you what is happening.
The calendar at a glance
| City (airport) | Normal onset | Normal withdrawal |
|---|---|---|
| Thiruvananthapuram (TRV) | 1 June | Northeast monsoon takes over |
| Chennai (MAA) | 4 June | Northeast monsoon takes over |
| Guwahati (GAU) | 4 June | 14 October |
| Goa, Panjim (GOI) | 7 June | 14 October |
| Hyderabad (HYD) | 8 June | 14 October |
| Mumbai (BOM) | 11 June | 8 October |
| Kolkata (CCU) | 11 June | 12 October |
| Ahmedabad (AMD) | 21 June | 30 September |
| Lucknow (LKO) | 23 June | 3 October |
| New Delhi (DEL) | 27 June | 25 September |
| Jaipur (JAI) | 1 July | 22 September |
All dates are IMD's revised normals from the 2020 release, retrieved 2026-09-27. For every other airport in the country, the India airports directory is the place to start.
How TrackMyWings helps
TrackMyWings™ is a flight-tracking platform in development. A private Android beta has been running on the Play internal testing track since 2026-08-24, and there is no public launch date yet. Gate and status alerts are among the features planned for launch; once they ship, they will be the way to hear about a monsoon-evening change to your flight, or to the flight of someone you are waiting for, without refreshing a page. Until then, the airport pages linked throughout this guide are the starting point for each city on the calendar.
Questions people ask
When does the monsoon start in India? On IMD's normal dates, the southwest monsoon sets in over Kerala on 1 June and covers the whole country by 8 July. Individual cities fall in between: Mumbai on 11 June, Delhi on 27 June.
When does the monsoon end? Withdrawal begins in extreme northwest India, not before 1 September by IMD's rule and on 17 September by the new normal for Jaisalmer. It finishes over south India by 15 October. Tamil Nadu's main rains then start with the northeast monsoon around 20 October.
Why does IMD's website show two different dates for the monsoon covering India? The onset explainer page still carries the older 15 July normal. IMD's 2020 revision moved it to 8 July, and the city table in that release is the current reference.
Is July the worst month to fly in India because of the monsoon? Not in a way a calendar can promise. July and August are when every region except the Tamil Nadu coast is inside the monsoon, so weather can come from either end of a trip. For Chennai, the wet months are October to December.
Sources
- India Meteorological Department, "New Normal Dates of Onset/Progress and Withdrawal of Southwest Monsoon over India" (2020 release with city table), https://mausam.imd.gov.in/backend/assets/press_release_pdf/IMD_Press_release_new_onset_and_withdrawal_dates(Final).pdf, captured 2026-09-27
- India Meteorological Department, "Monsoon Information: Onset," https://mausam.imd.gov.in/responsive/monsooninformation_onset.php, captured 2026-09-27
- India Meteorological Department, "Monsoon Information: Withdrawal," https://mausam.imd.gov.in/responsive/monsooninformation_withdrawal.php, captured 2026-09-27
- India Meteorological Department, Regional Meteorological Centre Chennai, "Report on Northeast Monsoon 2018," https://mausam.imd.gov.in/chennai/mcdata/ne_monsoon_2018.pdf, captured 2026-09-27
- Deccan Chronicle, "DGCA revises guidelines for monsoon flying" (published 2025-06-24), https://www.deccanchronicle.com/nation/current-affairs/dgca-issues-revised-safety-guidelines-for-monsoon-flying-amid-rising-weather-risks-1887196, captured 2026-09-27
Get TrackMyWings Early Access
Real-time flight tracking, gate change alerts, and family sharing: launching soon.