Northeast Monsoon Onset Likely in 2-3 Days
Why in News?
- On 12 October 2026, the India Meteorological Department said conditions are favourable for the onset of the northeast monsoon rains over the southern peninsula within two to three days.
- It expects a prolonged wet spell over the southern peninsula for five to six days after the onset.
- Isolated heavy rainfall is forecast for 15 to 18 October over Kerala and Mahe, coastal and south interior Karnataka, Tamil Nadu, Puducherry and Karaikal, and coastal Andhra Pradesh.
- The southwest monsoon is still withdrawing from the remaining parts of the country. It ended the season with 759.4 mm of rain, 12.6 per cent below the 868.6 mm normal, according to the report.
- On 30 September 2026, the department said post-monsoon rainfall is most likely to be normal over the south peninsula.
Key Terminologies
- Northeast monsoon
- The October-December rainy season of the southern peninsula. It follows the withdrawal of the southwest monsoon and brings rain to Tamil Nadu, Kerala, Karnataka, Andhra Pradesh and nearby areas.
- Monsoon withdrawal
- The retreat of the southwest monsoon from India, which the department tracks as a line moving across the country. In 2026 it began on 19 September from west Rajasthan.
- Long Period Average
- The benchmark rainfall against which a season is judged. The department classes a season below 90 per cent of this average as deficient.
- Post-monsoon season
- The period from October to December. The department issued its outlook for the season on 30 September 2026.
Key Issues
- Onset Timing: The department says conditions favour onset within two to three days of 12 October. After onset, rain should continue for five to six days over the southern peninsula.
- Weak Southwest Season: The 2026 southwest monsoon gave 87 per cent of the Long Period Average, and the South Peninsula received 542.0 mm, the 4th lowest since 1901. Rain from October therefore matters more for the south.
- Uneven Outlook: The department expects normal post-monsoon rainfall over the south peninsula, but below-normal rainfall over most other parts of India. Its October forecast for the country as a whole is also below normal.
- Heavy Rain Risk: Isolated heavy rainfall is forecast for coastal and south interior Karnataka, Tamil Nadu, Kerala and coastal Andhra Pradesh on 15 to 18 October, and for Rayalaseema on 15 and 16 October.
- Climate Driver: PTI attributes much of the southwest monsoon deficit to El Niño conditions over the Pacific. The World Meteorological Organization expects drier-than-normal conditions over the Indian subcontinent in October-December 2026.
Key Implications
Positive/Pros/Merits
- Rain for the South: A normal outlook over the south peninsula would help refill water bodies after a season with 76 per cent of average rainfall there. This is an inference from the data.
- Wet Spell Forecast: A prolonged wet spell of five to six days after onset suggests a good start to the season in the south.
- Lead Time: The department gave a window of two to three days and listed districts for heavy rain, which allows local authorities to prepare.
Negative/Cons/Demerits
- Rest of India Dry: Below-normal post-monsoon rainfall over most parts adds to the deficit left by the southwest season, with rabi sowing needing soil moisture.
- Heavy Rain Hazards: Isolated heavy rainfall in several southern States can cause waterlogging and flooding in cities and low-lying areas. This is an inference.
- Forecast Uncertainty: The forecast for October is probabilistic, and El Niño is strengthening, so local outcomes may differ from the seasonal outlook.
Key Initiatives
- India Meteorological Department Outlook, 30 September 2026: It forecast normal post-monsoon rainfall over the south peninsula and below-normal rainfall for most of the rest of India.
- India Meteorological Department Forecast, 12 October 2026: It said onset of the northeast monsoon is likely over the southern peninsula in two to three days, with heavy rain alerts for 15 to 18 October.
- Mission Mausam: The Ministry of Earth Sciences mission was approved with Rs 2,000 crore over two years. Phase-I runs 2024-26 and Phase-II 2026-31, with next-generation radars and finer models.
- World Meteorological Organization, 8 October 2026: Its update says El Niño is strengthening, and that drier-than-normal conditions are more likely over the Indian subcontinent.
The India Meteorological Department says conditions are favourable for the onset of the northeast monsoon over the southern peninsula, and that the southwest monsoon is still withdrawing from the remaining parts of the country. It has issued heavy rainfall outlooks for specific southern States. The Ministry of Earth Sciences continues Mission Mausam, which moves to Phase-II in 2026-31.
Director's Perspective
Way Forward
- Issue district-level flood and waterlogging alerts for 15 to 18 October in the listed southern States, with drain clearing in advance.
- Release reservoir and tank levels in the south weekly, so water managers can plan around a normal-rain outlook.
- Give rabi farmers outside the south soil moisture advisories, because the outlook for most other regions is below normal.
The forecast is good news for the south and a caution for the rest of India. The southern peninsula can expect normal rain after a weak southwest season, but most other regions face a below-normal outlook, and heavy-rain spells carry flood risk. The department's lead time is useful, but El Niño keeps uncertainty high. In a Mains answer, credit the early warning and Mission Mausam, then conclude that regional planning for water and floods must follow the uneven rainfall.
GS Relevance
Frequently Asked Questions
When will the northeast monsoon start in 2026?
The India Meteorological Department said on 12 October 2026 that conditions are favourable for onset of the northeast monsoon rains over the southern peninsula within two to three days. A prolonged wet spell of five to six days is expected after onset.
What is the northeast monsoon?
The northeast monsoon is the October-December rainy season of the southern peninsula, which follows the withdrawal of the southwest monsoon. The department expects normal rainfall over the south peninsula in 2026, while most other parts of India may receive below-normal rain.
How much rain did the southwest monsoon bring in 2026?
The 2026 southwest monsoon brought 759.4 mm of rain, which is 87 per cent of the Long Period Average and the 4th lowest since 2001. The South Peninsula received 542.0 mm, the 4th lowest since 1901, according to the India Meteorological Department.
PYQ Practice — Statement Analysis
1 The northeast monsoon brings rain to the southern peninsula during October to December.
The India Meteorological Department expects normal post-monsoon rainfall there in 2026.
2 The India Meteorological Department expects above-normal post-monsoon rainfall over most of India in 2026.
It expects below-normal rainfall over most parts, with normal rainfall over the south peninsula.
3 A seasonal rainfall below 90 per cent of the Long Period Average is classed as deficient.
The 2026 southwest monsoon at 87 per cent fell in this class.