Kerala likely to experience harsh summer as two monsoons play truant

With barely a week remaining before the formal withdrawal of the northeast monsoon, Kerala is likely to record a deficient northeast monsoon season this year (2025). The shortfall in rain is also expected to strain reservoir water levels during the upcoming summer in 2026.

The northeast monsoon, which usually begins around October 1 and lasts until December 31, is currently 20% deficient as of December 24, with Kerala netting just 388.3 mm of rain against the average of 487.2 mm during the same period. 

Given the atmospheric conditions, the State will likely not experience any major showers during the remaining season, as the Bay of Bengal is relatively calm except for a weak easterly wave prevailing over its southern region. In addition, the southwest monsoon, which brings the major share of the monsoon rainfall in Kerala during the June-September period, was also 13% less this year. The shortfall in rains during the two major monsoon seasons in a year may lead to water shortage during summer, along with increased temperature, unless there are any major summer spells.

For instance, as of December 23, the active storage in the Idukki reservoir was 75.23%, while the active storage at the Banasurasagar dam in Wayanad was 70.52%.

Weak La Niña conditions

Meanwhile, the extended forecast issued by the India Meteorological Department (IMD) warned of below-normal rainfall coupled with below-normal minimum temperatures in Kerala during the remaining period in December. Currently, weak La Niña conditions are prevailing over the equatorial Pacific region. According to the latest climate update of the Bureau of Meteorology, Australia, the tropical Pacific Ocean temperatures are likely to remain at La Niña levels until early 2026 before returning to neutral. 

For India, La Niña generally brings cooler winters and stronger monsoons. According to the World Meteorological Organisation (WMO), La Niña refers to the periodic large-scale cooling of the ocean surface temperatures in the central and eastern equatorial Pacific Ocean, coupled with changes in the tropical atmospheric circulation, including changes in winds, pressure and rainfall patterns. Considering the atmospheric parameters, the night and early morning temperatures in Kerala will be below normal during this winter and relatively higher during the daytime.

For instance, amid the dropping mercury at night, Kottayam recorded the highest day temperature of 35.5 degrees Celsius on December 23. On the other hand, Letchmi Estate in Munnar recorded the lowest temperature of minus 1 degree Celsius for the second consecutive day on Wednesday.