Southern peninsular India faced an alarming weather situation this year, with the India Meteorological Department (IMD) declaring October as the sixth driest in 123 years. The region, encompassing Kerala, Mahe, south interior Karnataka, Tamil Nadu, Karaikal, Puducherry, coastal Andhra Pradesh, Yanam, and Rayalaseema, received a mere 74.9mm of rainfall, marking a significant 60% drop below the normal average.
Weather Anomalies and Their Impact
Southern peninsular India typically witnesses rainfall in October from both the retreating southwest monsoon and the incoming northeast monsoon. However, this year was an exception, as the region remained dry for nearly 25 days throughout October. Unlike the past few years, the southwest monsoon concluded promptly after a 134-day season.
One of the primary factors contributing to this inadequate rainfall was the timing of the northeast monsoon, which coincided with other oceanic factors. The onset of the northeast monsoon occurred on October 21, and during the same period, an active Bay of Bengal and the development of Cyclone Hamoon influenced the monsoon onset.
Regional Rainfall Data
As of October 31, the IMD reported the following rainfall figures:
- Coastal Andhra Pradesh and Yanam: 18mm (90% below normal)
- Rayalaseema: 12.7mm (90% below normal)
- Tamil Nadu, Karaikal, and Puducherry: 98.5mm (43% below normal)
- South interior Karnataka: 64.5mm (53% below normal)
- Kerala: 311mm (1% below normal)
El Nino and Indian Ocean Dipole
The IMD highlighted that 2023 is an El Nino year, and when combined with the positive phase of the Indian Ocean Dipole (IOD), such rainfall deficits are commonly observed in October. El Nino and positive IOD phases result in reduced rainfall in northern Tamil Nadu and adjoining areas, while the southernmost regions of Tamil Nadu and Kerala experience more significant rainfall during this month.
