Mint Explainer: South India pins hope on northeast monsoon for rainfall relief

What is the northeast, or retreating, monsoon, and when does it usually occur?

The northeast, or retreating, monsoon is a seasonal wind shift that follows the southwest monsoon. As the southwest monsoon withdraws, winds over southern India change direction. This brings moisture and rain mainly during October–December. It matters because these months provide a major share of annual rainfall for southern states.

Unlike the southwest monsoon, which affects much of India, the northeast monsoon is especially important for South Peninsular India. Andhra Pradesh, Karnataka, Kerala, Tamil Nadu and Telangana rely on this later-season rain for water supplies, farming and reservoir recovery. The article says the season typically begins in October.

For 2026, the IMD expects October–December rainfall in South Peninsular India to be normal, meaning 88–112% of its long-period average. However, El Niño is strengthening, and most of India may receive below-normal rainfall. The northeast monsoon will therefore be closely watched after the region’s weak southwest monsoon.

How large was South Peninsular India’s rainfall deficit during the June–September southwest monsoon?

South Peninsular India recorded a 24.3% rainfall deficit during the June–September southwest monsoon. It received 542.0mm, equal to only 76% of its long-period average. This shortfall is significant because the region includes Andhra Pradesh, Karnataka, Kerala, Tamil Nadu and Telangana, all of which depend on seasonal rain for water and agriculture.

The deficit was not merely a small variation from normal. It made the region’s southwest monsoon the fourth-lowest since 1901 and the second-lowest since 2001. Nationally, India received 87% of its long-period average, or 759.4mm. South Peninsular India therefore performed considerably worse than the country overall.

The weak season leaves the region dependent on the northeast monsoon. The IMD forecasts normal October–December rainfall for the region, but strengthening El Niño conditions create uncertainty. If later rains disappoint, water supplies, irrigation and rabi farm preparations could come under further pressure.

Why do Andhra Pradesh, Karnataka, Kerala, Tamil Nadu and Telangana depend so heavily on October–December rainfall?

Andhra Pradesh, Karnataka, Kerala, Tamil Nadu and Telangana are grouped as South Peninsular India. They depend heavily on October–December rainfall because the northeast monsoon supplies a significant share of their annual rain. This season can replenish reservoirs, improve soil moisture and support agriculture after the southwest monsoon ends.

The need is especially clear in 2026. The region received only 542.0mm during June–September, or 76% of its long-period average. Its rainfall was the fourth-lowest since 1901. With less water collected during the main monsoon, the October–December season has a larger job than usual.

The IMD forecasts normal northeast monsoon rainfall for South Peninsular India, at 88–112% of the long-period average. That could help restore water availability and support farm operations. Yet the region’s reservoirs are already depleted, and El Niño is strengthening. A weak late monsoon would therefore intensify water and agricultural stress.

How do the region’s low reservoir levels affect its ability to withstand another weak rainfall season?

Low reservoir storage reduces the region’s buffer against another weak rainfall season. Reservoirs provide water for cities, farms and industry when rain is irregular. When levels begin low, even normal demand can rapidly reduce available supplies. This makes the timing and strength of the northeast monsoon especially important.

The southern region’s 50 monitored reservoirs held 49.15% of their combined 55.879 billion cubic metres capacity on 1 October. That was sharply below 87.82% a year earlier and the normal level of 76.28%. The figures show that the region entered the northeast monsoon with far less stored water than usual.

If October–December rainfall is weak, reservoirs may receive little recharge. Irrigation systems could face greater pressure, and farmers may depend more on groundwater or reduce planting. The IMD expects normal rainfall in South Peninsular India, but strengthening El Niño conditions and already-low storage leave limited room for error.

What role do the India Meteorological Department and climate models play in forecasting the northeast monsoon?

The India Meteorological Department provides the official seasonal forecast. It estimates whether October–December rainfall over South Peninsular India will be below normal or above normal. In this case, the IMD says normal rainfall is most likely, defined as 88–112% of the long-period average.

Climate models help build that outlook by simulating ocean and atmosphere conditions. The Monsoon Mission Coupled Forecast System, along with other major models, indicates that El Niño will strengthen through the end of 2026. El Niño is a key climate signal that can influence monsoon circulation and rainfall patterns. Forecasters use such signals alongside other information.

The forecast is therefore encouraging but not risk-free. The IMD expects normal rain in the south, while most parts of India are expected to receive below-normal rainfall. The strengthening El Niño signal, depleted southern reservoirs and earlier rainfall deficit make updates important as the season progresses.

How could below-normal rainfall affect rabi sowing, crop yields and food inflation?

Rabi crops are planted after the monsoon and need adequate soil moisture, irrigation and water supplies. Below-normal rainfall can reduce all three. Farmers may have to delay sowing, increase irrigation or leave some land uncultivated. These problems are most serious in rain-fed areas, where crops depend directly on stored soil moisture and rainfall.

The article identifies several possible effects: dry spells, moisture stress, lower agricultural productivity and reduced recharge of reservoirs and groundwater. Lower yields can reduce supplies of food crops. If demand remains steady while supplies weaken, prices may rise. This can transmit weather stress from farms to household food budgets.

The risk matters because food inflation already reached 5.95% in August, pushing retail inflation to a 20-month high of 4.82%. The IMD expects normal northeast monsoon rain in the south, which could limit damage there. But a broader rainfall shortfall could still affect rabi preparations, output and inflation.

How do monsoons work, and why can El Niño alter their strength and distribution across India?

A monsoon forms when land and ocean heat differently across seasons. In summer, heated Asian land draws in moisture-laden winds from the ocean, producing the southwest monsoon. In autumn, land cools and winds reverse, helping produce the northeast, or retreating, monsoon. Rainfall varies because pressure, winds, moisture and local geography change across regions.

El Niño is a warming of the central and eastern equatorial Pacific Ocean. It can alter the global circulation of air and shift the rising and sinking branches that help drive monsoon winds. As a result, moisture transport toward India may weaken or change location. The effects are not identical everywhere, so some regions can receive less rain while others fare better.

The article reports strong El Niño conditions and forecasts that they will strengthen through year-end. India’s 2026 southwest monsoon reached only 87% of its long-period average. The IMD expects normal northeast monsoon rain in the south, but most of India may remain below normal.

Key Facts:

📌 The northeast monsoon usually begins in October.

📌 It is also called the retreating monsoon.

📌 South India receives significant annual rainfall during October–December.

📌 South Peninsular India recorded a 24.3% southwest monsoon deficit.

📌 The region received 542.0mm, or 76% of its long-period average.

📌 Its rainfall was the fourth-lowest since 1901.

📌 October–December rainfall provides a significant share of southern India’s annual rain.