Tamil Nadu has experienced above-normal rainfall this January with Chennai receiving significantly higher than average rainfall. The state recorded 23.4 mm of rain from January 1 to 20, 127% above the usual 10.3 mm, as per a Skymet Weather report.
Weather blogger Pradeep John attributed this unusual pattern to the Madden-Julian Oscillation (MJO), a tropical disturbance influencing rainfall over Africa, the Indian Ocean, and parts of India, as per a report on Times of India.
This year’s prolonged monsoon echoes patterns from previous years, such as 2004-05, when rains lasted until January 25, and 2021, when the season extended to January 22, 2022. The average onset of the northeast monsoon is October 20 (±8 days), with withdrawal around December 20 (±14 days).
Why Is Monsoon Extended?
The prolonged rains are linked to favorable oceanic phenomena, including La Niña and the Madden-Julian Oscillation (MJO), as per a report on Times Now. La Niña, which has been active for some time, typically enhances northeast monsoon activity. The MJO, a weather pattern oscillating across the Indian Ocean, has consistently lingered in the region, intensifying rainfall over Tamil Nadu.
Currently, the MJO is moving eastward across the Indian Ocean and is expected to stay in a favourable phase for approximately the next 10 days, lasting until the end of January, as per Skymet.
The IMD which began officially announcing monsoon withdrawal dates in 1993 considers factors such as rainfall, moisture depth and temperature to determine the cessation of the season.
On Wednesday, IMD has predicted light to moderate rain in isolated parts of South Tamil Nadu, while North Tamil Nadu, Puducherry, and Karaikal are likely to experience dry weather. Morning mist or haze is expected in isolated pockets across Tamil Nadu, including Chennai, where misty mornings have become a common sight.
On Tuesday, the IMD reported very light rainfall in Ramanathapuram and Virudhunagar districts with dry weather prevailing elsewhere. This comes amid an extended northeast monsoon season which typically concludes by December but has continued into January this year.