Keralam witnesses 7th-lowest southwest monsoon season
Keralam has closed the southwest monsoon season with a marked rainfall shortfall, recording 1,446.5 mm of rain against a seasonal norm of 2,018.6 mm—an overall deficit of 28%. The prolonged shortfall has left large parts of the State facing drought-like conditions and placed added strain on water resources and agriculture.
Season overview and historical ranking
The southwest monsoon, which concluded on September 30, registered as Keralam’s seventh-lowest seasonal rainfall since 1901 and the fourth-lowest since 2001. India Meteorological Department (IMD) data show that nearly 70% of the State ended the season in significant rain deficiency. Eight districts reported shortfalls ranging from 20% to 53%, while six had deficits between 0% and 20%.
Among the hardest hit were Idukki and Wayanad—districts critical to Keralam’s network of large reservoirs and hydropower generation—which each received around 50% less rain than normal. The widespread and persistent deficit has raised concerns about water availability, reservoir storage levels and power generation through the coming months.
Uneven monsoon marked by prolonged dry spells
The defining feature of this southwest monsoon was its uneven rainfall distribution across the State. The season saw fewer rain-producing systems develop over the Bay of Bengal, resulting in extended dry periods punctuated by brief, high-intensity spells. This pattern hampered effective groundwater recharge, which typically relies on sustained, low- to moderate-intensity rainfall rather than short bursts of heavy precipitation.
The strain was most apparent by the end of July. By July 31, Keralam had recorded only 853.8 mm of rain, compared with the normal 1,301.7 mm for the period—a deficit of 34%. A subsequent burst of heavy rain over four days, aided by a depression over central India, temporarily narrowed the gap. By August 4, cumulative rainfall had increased to 1,059.6 mm against a normal of 1,374.9 mm for the June 1–August 4 period, bringing the deficit down to 23%. Even so, the improvement was short-lived.
Towards the end of July, a tropical storm and, in the first week of August, a strong offshore trough triggered heavy rainfall in several parts of Keralam, notably in Idukki and Kottayam. In Wayanad, the intense rain coincided with a devastating debris slip. Despite these high-impact events, broad swathes of the State continued to experience rainfall stress, and the season’s cumulative deficit persisted.
District deficits and hydropower implications
The concentration of heavy rain during isolated episodes did little to alleviate the overall shortage across districts. With eight districts in the 20%–53% deficit band and six others between 0% and 20%, the geographic spread of shortfalls underscored the unevenness of the monsoon’s performance. The situation in Idukki and Wayanad is particularly consequential: both districts host major reservoirs and are central to Keralam’s hydropower capacity. With inflows reduced by the substantial deficit, energy planners and water managers are expected to face tighter operating conditions across the post-monsoon months.
Northeast monsoon outlook
Attention now turns to the northeast monsoon, which typically sets in by mid-October. While it could bring some relief, the latest forecast suggests below-normal rainfall during the opening month of the season. The emerging El Niño over the equatorial Pacific is expected to influence rainfall distribution and intensity.
According to the IMD’s extended-range outlook, no major rainfall is indicated for Keralam over the next four weeks. However, central and southern parts of the State are projected to receive normal to slightly above-normal rainfall in November and during the remainder of the northeast monsoon season, a development that could help bridge October’s shortfall.
El Niño’s influence and potential weather systems
The northeast monsoon, unlike the southwest monsoon, does not follow a fixed pattern and depends largely on the formation and movement of depressions and storms over the Bay of Bengal. El Niño—currently at near-record levels—could further modify this pattern. Climate experts note that prevailing oceanic and atmospheric indicators are consistent with a strong El Niño, a setup that may favor the development of more weather systems over the Bay of Bengal or the Arabian Sea. If that transpires, Keralam could experience intense rainfall spells interspersed with prolonged dry periods through the season.
What to watch next
With the southwest monsoon ending in significant deficit and the early northeast monsoon expected to be subdued, water managers and local administrations will be closely monitoring reservoir levels, groundwater trends, and short- to medium-range forecasts. Any strengthening of Bay of Bengal or Arabian Sea systems in November could provide crucial inflows, particularly in central and southern districts.
Conclusion
Keralam’s 2026 southwest monsoon ranks among its weakest in more than a century, marked by a 28% rainfall deficit, pronounced geographic unevenness, and sustained dry spells that impeded groundwater recharge. While the northeast monsoon offers a chance for partial recovery—especially later in the season—the evolving El Niño and the inherently variable nature of the northeast monsoon mean the State’s drought-like conditions and water-resource pressures will likely persist in the near term. Close monitoring and adaptive water management will be essential until more consistent rainfall materializes.
