Southern Peninsular India Experiences Sixth Driest October in 123 Years

November 1, 2023

In an unusual meteorological event, southern peninsular India faced its sixth driest October in 123 years, according to the India Meteorological Department (IMD). This region, encompassing states like Kerala, Mahe, south interior Karnataka, Tamil Nadu, Karaikal, Puducherry, coastal Andhra Pradesh, Yanam, and Rayalaseema, received a meager 74.9mm of rainfall in October. This amount was more than 60 percent below the normal levels for the month.

Monsoons and Their Role

October typically witnesses rainfall in southern peninsular India due to both the retreating southwest monsoon and the incoming northeast monsoon. However, this year, the region remained dry for nearly 25 days during October. Unlike previous years, the southwest monsoon concluded nearly on time after a 134-day season.

Influencing Factors

One of the main contributors to this scanty rainfall was the timing of the northeast monsoon coinciding with other oceanic factors. The onset of the northeast monsoon occurred on October 21, closely aligning with active conditions in the Bay of Bengal and the formation of Cyclone Hamoon. These factors led to the diversion of moisture away from southern peninsular India and altered the wind flow pattern, resulting in a weak northeast monsoon onset.

October Rainfall Statistics

As of October 31, the IMD reported the following October rainfall figures: coastal Andhra Pradesh and Yanam (18mm, -90 percent), Rayalaseema (12.7mm, -90 percent), Tamil Nadu, Karaikal, and Puducherry (98.5mm, -43 percent), south interior Karnataka (64.5mm, -53 percent), and Kerala (311mm, 1 percent).

Influence of El Nino and Indian Ocean Dipole (IOD)

The IMD noted that 2023 being an El Nino year, coupled with the positive phase of the Indian Ocean Dipole (IOD), often leads to such rainfall deficits in October, as observed in previous El Nino years like 2023, 2016, and 1988. During El Nino years and the positive IOD phase, there tends to be reduced rainfall in northern Tamil Nadu and nearby regions, while the southernmost parts of Tamil Nadu and Kerala receive more significant rainfall in October.

Hope for Improved Rainfall

Despite the dry start, the northeast monsoon has gained momentum in the past few days. The IMD forecasts widespread good rainfall over Kerala and Tamil Nadu in the upcoming week. Additionally, the rainfall outlook for November in the region is promising. The IMD anticipates that monthly rainfall during November over southern peninsular India will likely be normal, ranging between 77 to 123 percent of the Long Period Average (LPA), which is 118.69mm based on data from 1971 to 2020.

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