Editorial: A 'normal' northeast monsoon in a strong El Niño year can still bring floods
In one line: After a 12.6% deficit in the summer monsoon, IMD expects a normal northeast monsoon for the south, but The Hindu warns that a wide 'normal' band in a strong El Niño year can still hide destructive rain.
Published 26 October 2026. Written by Pratidin from the reports linked at the end; every fact checked by a separate review before publishing. How we work
The Hindu's editorial 'Wicked surprise' on 26 October 2026 turns to the northeast monsoon after a poor southwest monsoon. June to September rainfall in 2026 was 759.4 mm against a normal of 868.6 mm, a 12.6% deficit and the driest season in 11 years, which hurt kharif sowing and food prices. The southern peninsula now depends on the October to December rains. On 1 October the India Meteorological Department (IMD) forecast that rainfall over South Peninsular India this season is most likely to be 'normal', that is 88% to 112% of the Long Period Average (LPA) of about 334.13 mm based on 1971 to 2020 data. It expects normal to above-normal rain over southern Kerala and Tamil Nadu and below-normal rain over most other parts of the region.
The southwest monsoon withdrew from the whole country on 15 October 2026, and northeast monsoon rains began the same day over Tamil Nadu, Puducherry and Karaikal, coastal Andhra Pradesh, Rayalaseema, south interior Karnataka, and Kerala and Mahe. Tamil Nadu receives about 48% of its annual rainfall in these three months. The backdrop is a strong El Niño in the equatorial Pacific, which IMD says is likely to strengthen through the end of 2026 and continue into early 2027, while the Indian Ocean Dipole (IOD) is neutral. El Niño tends to weaken the southwest monsoon, but its link with northeast monsoon rain is less consistent.
The editorial's warning is about what 'normal' hides. It argues that a band of plus or minus 12% around the average is much wider than the error margin of IMD's southwest monsoon forecasts, so a 'normal' season can still contain extreme spells. It recalls that the catastrophic Chennai floods of December 2015 came in a strong El Niño year. It asks States to clear stormwater drains, strengthen shelters, plan for damage to infrastructure and sharpen local warnings before the peak of the season. The underlying point for policy is that drought and flood preparedness are not alternatives: a deficient summer monsoon and intense winter rain can hit the same region in the same year.
Prelims facts
- The 2026 southwest monsoon gave 759.4 mm against a normal of 868.6 mm, a 12.6% deficit.
- IMD forecasts 'normal' October to December rain (88% to 112% of an LPA of about 334.13 mm) over South Peninsular India.
- The southwest monsoon withdrew from the country on 15 October 2026, the same day northeast monsoon rains began over the southern peninsula.
- Tamil Nadu receives about 48% of its annual rainfall during the northeast monsoon.
- IMD expects the strong El Niño to persist into early 2027, with the Indian Ocean Dipole neutral.
Quick recall
- Southwest monsoon 2026: actual and normal rainfall?
- 759.4 mm against a normal of 868.6 mm, a 12.6% deficit.
- IMD's 'normal' range for the northeast monsoon over South Peninsular India?
- 88% to 112% of the LPA.
- LPA of October to December rainfall over South Peninsular India?
- About 334.13 mm, based on 1971 to 2020.
- On what date did the southwest monsoon withdraw from the whole country in 2026?
- 15 October 2026.
- What share of Tamil Nadu's annual rainfall comes in the northeast monsoon?
- About 48%.
- State of the IOD in IMD's 1 October 2026 outlook?
- Neutral, likely to stay neutral through the season.
- Which major flood came in a strong El Niño year and is cited by the editorial?
- The Chennai floods of December 2015.
- Where does IMD expect normal to above-normal rain this season?
- Southern Kerala and Tamil Nadu.
Prelims practice question
In IMD's outlook for the 2026 northeast monsoon, 'normal' rainfall over South Peninsular India is defined as rainfall within what range of the Long Period Average?
- 96% to 104%
- 90% to 110%
- 88% to 112%
- 80% to 120%
Show answer
Answer: (c) 88% to 112%. IMD's 1 October 2026 outlook says the October to December rainfall over South Peninsular India is most likely to be normal, defined as 88% to 112% of the LPA (about 334.13 mm, based on 1971 to 2020). The 96% to 104% band is used for 'normal' in the all-India southwest monsoon forecast.
Use this in UPSC Mains: previous-year questions
Recurring theme: Monsoon variability, ENSO and preparedness for hydro-meteorological disasters
- How to use this
Use 2026 to show that El Niño explains some anomalies, like the summer deficit, but not all, since its northeast monsoon link is inconsistent.
- Under a strong El Niño, the 2026 southwest monsoon gave 759.4 mm against 868.6 mm normal, a 12.6% deficit.
- Yet IMD forecast a normal northeast monsoon (88% to 112% of LPA) for South Peninsular India, with a neutral IOD.
- The December 2015 Chennai floods came in a strong El Niño year, showing El Niño does not mean dry everywhere.
Urban flooding in Chennai shows how changes to the landscape amplify the impact of monsoon rain.
IMD's 2026 outlook notes a neutral IOD alongside a strong El Niño, directly relevant to how the IOD can modify El Niño's effect.
Mains practice question
El Niño is usually associated with drought in India, yet southern India often faces floods in El Niño years. Explain the northeast monsoon and discuss the preparedness needed for its extremes. (250 words)
Model answer
The 2026 southwest monsoon ended 12.6% below normal (759.4 mm against 868.6 mm) under a strong El Niño. Yet IMD forecasts a 'normal' northeast monsoon, and The Hindu's editorial warns of extreme rain.
The northeast monsoon
- October to December rains after the southwest monsoon withdraws and winds turn north-easterly.
- Confined mainly to Tamil Nadu, Puducherry, coastal Andhra Pradesh, Rayalaseema, south interior Karnataka and Kerala.
- Tamil Nadu gets about 48% of its annual rain in this season.
- Rain comes largely from low-pressure systems and cyclones in the Bay of Bengal, which peak in this period.
- 2026: onset of rains on 15 October; IMD forecasts 88% to 112% of an LPA of about 334.13 mm.
Why El Niño matters differently
- El Niño weakens the southwest monsoon.
- Its link with northeast monsoon rain is weaker and inconsistent; the December 2015 Chennai floods came in a strong El Niño year.
- IOD and the Madden-Julian Oscillation also shape the season.
Preparedness
- Urban drainage: desilt stormwater drains and protect lakes and natural channels from encroachment.
- Early warning: localised, impact-based alerts and reservoir release protocols.
- Shelters and response: pre-positioned State and National Disaster Response Forces, cyclone shelters, evacuation plans.
- Agriculture: contingency crop plans for both deficit and excess.
- Institutions: implement NDMA urban flood guidelines and city-level flood plans.
Conclusion
A 'normal' forecast is an average, not a guarantee; the south must plan for drought and deluge in the same year.
The basics
Why this matters
Most Indians think of the monsoon as June to September. For Tamil Nadu and parts of the south, the season that matters most comes later. The Northeast monsoon decides whether Chennai's reservoirs fill and whether its streets flood. In 2026 it arrives after a weak summer monsoon and during a strong El Niño, which makes it both more needed and harder to predict.
Two monsoons, one peninsula
The southwest monsoon brings moist winds from the Arabian Sea and Bay of Bengal across most of India. As it withdraws in October, winds over the south turn north-easterly, and the Bay of Bengal becomes the source of rain for the south-east coast.
- June to September
- Covers most of India
- Weakened by El Niño
- 2026: 12.6% below normal
- October to December
- Mainly Tamil Nadu, Puducherry, coastal Andhra, Rayalaseema, south interior Karnataka, Kerala
- Link with El Niño weaker and inconsistent
- Rains began 15 October 2026
Reading an IMD forecast
IMD compares seasonal rain with a Long Period Average (LPA) and gives a category. For the northeast monsoon over South Peninsular India, 'normal' means 88% to 112% of the LPA of about 334.13 mm. That band is wide, which is the editorial's point: 'normal' can include very wet weeks.
The flood risk
Rain in this season often comes from depressions and cyclones over the Bay of Bengal, which can dump a month's rain in a day. When drains are clogged and lakes built over, Urban flooding follows, as Chennai saw in December 2015, a strong El Niño year. The Indian Ocean Dipole and other factors also shape how much rain falls.
The takeaway for an answer: El Niño does not mean 'dry' everywhere, and a normal forecast is not a safety certificate.
Go deeper
Why it matters for UPSC
The monsoon is core GS1 geography and Prelims material, and floods are core GS3 disaster management. This editorial links the two, and adds a current example of how El Niño affects India unevenly.
The core idea
The Northeast monsoon brings October to December rain to the south-east of the peninsula. El Niño usually weakens the southwest monsoon but has an inconsistent link with the northeast monsoon. IMD judges a season against its Long Period Average; a 'normal' forecast still allows wide swings. Because much of this season's rain comes from intense Bay of Bengal systems, the main risk is Urban flooding. The Indian Ocean Dipole, neutral this year, is another driver to watch.
Numbers and dates to remember
- Southwest monsoon 2026: 759.4 mm against 868.6 mm normal (minus 12.6%).
- IMD outlook (1 October): normal, 88% to 112% of an LPA of about 334.13 mm.
- 15 October 2026: southwest monsoon withdrew; northeast monsoon rains began.
- Tamil Nadu: about 48% of annual rain in October to December.
- December 2015: Chennai floods in a strong El Niño year.
Where to go next
- Northeast monsoon: how the winter monsoon works.
- El Niño: the Pacific warming behind this year's weather.
- Long Period Average: how to read an IMD forecast.
- Indian Ocean Dipole: the Indian Ocean's own see-saw.
- Urban flooding: why cities drown in a normal season.
Go deeper: why 'normal' is not reassuring
The editorial's sharpest point is statistical. The 'normal' band for the Northeast monsoon is 88% to 112% of the Long Period Average, a range of 24 percentage points. It contrasts this with the much tighter error margin of IMD's southwest monsoon forecasts. A season can end within 'normal' while containing a few days of extreme rain, and it is those days that cause floods.
The second point is physical. El Niño is the warming of the central and eastern equatorial Pacific. It shifts rising air away from the Indian region in summer, weakening the southwest monsoon, as in 2026. Its effect on the northeast monsoon runs through different mechanisms and is less reliable: some El Niño years have brought heavy rain to Tamil Nadu and others have not. The December 2015 Chennai floods came in a strong El Niño year. The Indian Ocean Dipole and the Madden-Julian Oscillation can strengthen or offset these effects.
The third point is human. Damage depends on exposure as much as on rain. Urban flooding in Chennai has been linked to construction on lakes, wetlands and floodplains and to clogged drains. Hence the editorial's practical agenda: clear stormwater drains, strengthen shelters, prepare for damage to infrastructure and sharpen local warnings.
A balanced answer should also note the other side of the risk. IMD expects below-normal rain over most of the region outside southern Kerala and Tamil Nadu, so drought management, reservoir operation and contingency crop plans remain necessary. The south may face both deficit and excess in the same year.
Northeast monsoon
How the winter monsoon of the south-east works.
In one line: The northeast monsoon is the October to December rainy season of the south-eastern peninsula, when winds turn north-easterly after the southwest monsoon withdraws.
How it works
As the southwest monsoon retreats, the wind over the south turns north-easterly. These winds cross the Bay of Bengal and bring rain to the east coast. October to December is also the peak season for depressions and cyclones over the north Indian Ocean, which bring much of the rain. Tamil Nadu receives about 48% of its annual rainfall in this season.
The 2026 season
The rains began on 15 October 2026 over Tamil Nadu, Puducherry and Karaikal, coastal Andhra Pradesh, Rayalaseema, south interior Karnataka, and Kerala and Mahe. IMD forecasts a normal season overall.
Where to go next
El Niño
The Pacific warming behind this year's weather.
In one line: El Niño is the periodic warming of sea surface waters in the central and eastern equatorial Pacific, the warm phase of the El Niño Southern Oscillation (ENSO).
Effects on India
During El Niño, the zone of rising air and rain shifts eastward over the Pacific, which tends to weaken the Indian southwest monsoon. Many Indian droughts have occurred in El Niño years, and 2026's 12.6% deficit came under a strong El Niño. The link with the northeast monsoon is weaker and inconsistent. La Niña, the cool phase, has the opposite tendencies.
Why it is in the news
IMD's 1 October 2026 outlook says a strong El Niño is present and likely to strengthen through the end of 2026 and continue into early 2027.
Where to go next
Long Period Average
How to read an IMD seasonal forecast.
In one line: The Long Period Average (LPA) is the average rainfall for a region and season over a long base period, against which IMD measures and forecasts each season.
How categories work
IMD expresses seasonal rain as a percentage of the LPA and puts it in categories such as deficient, below normal, normal and above normal. For the northeast monsoon over South Peninsular India, the LPA is about 334.13 mm (1971 to 2020) and 'normal' is 88% to 112% of it. The all-India southwest monsoon uses a narrower normal band of 96% to 104%.
Why it matters
A wide band means a 'normal' forecast carries less information about extremes. The Hindu's editorial argues that this is why States should not relax.
Where to go next
Indian Ocean Dipole
The Indian Ocean's own temperature see-saw.
In one line: The Indian Ocean Dipole (IOD) is the difference in sea surface temperature between the western and eastern tropical Indian Ocean.
Phases
In a positive IOD, the western Indian Ocean is warmer than the east; this tends to support Indian rainfall and can offset El Niño's drying effect. In a negative IOD the pattern reverses. A neutral IOD means neither side is unusually warm.
Why it is in the news
IMD's 1 October 2026 outlook says neutral IOD conditions prevail and are likely to continue through the northeast monsoon season, so the IOD is not expected to add to or offset El Niño's influence this year.
Where to go next
Urban flooding
Why cities drown even in a 'normal' season.
In one line: Urban flooding is the inundation of built-up areas when intense rain exceeds the capacity of drains and natural channels.
Why it happens
Cities replace soil and wetlands with concrete, so rain runs off quickly instead of soaking in. Encroachment on lakes, floodplains and stormwater channels, and silted drains, reduce the space for water. A few hours of very heavy rain can then flood large areas, regardless of whether the season's total is normal.
Why it is in the news
The Hindu's editorial recalls the December 2015 Chennai floods and asks States to clear stormwater drains, strengthen shelters and improve local warnings before the peak of the 2026 northeast monsoon.
Where to go next
Take the 26 October 2026 quiz: 30 Prelims-style questions with answers