Monsoon Knock Over South Andaman Sea Anytime Soon, Further Rapid Advance Likely

Cross-equatorial flow is becoming fairly strong all along the equatorial region of the Indian Ocean adjacent to the South Bay of Bengal (BoB) (Please Read: https://www.skymetweather.com/content/climate-change/enso-neutral-and-weak-mjo-offer-no-push-for-monsoon-monsoon-entry-starts-mid-may).

Also, a small-scale perturbation is coming up over the extreme south-central Bay of Bengal. This will enhance the flow to increase the spread and intensity. As such, coastal parts of Thailand, next to the South Andaman Sea, have been observing monsoonal rains. Places like Phuket and Takua Pa on the southernmost coast have recorded three-digit rainfall in the past 24 hours. More drenching showers are likely in the next few days. Bay Islands like Nancowry and Hut Bay have recorded moderate rainfall. Conditions are becoming favourable for the incursion of monsoon streams over these parts anytime soon.

The monsoon current normally advances over the South Andaman Sea and the extreme Southeast Bay of Bengal by 15th May. It further moves to reach the North Andaman Sea and South-Central BoB by 22nd May.  Next stop, Sri Lanka on the west and the South Arakan Coast on the eastern flank, across Southeast BoB, is slated for 26th May. The scheduled arrival over mainland Kerala is 01st June with a standard deviation of one week.

The southwest monsoon may enter the South Andaman Sea, a little before time, within the next 48 hours.

Must Read: Pre-Monsoon Weather Activity To End Soon Over Gujarat, Heat Wave Likely Next Week

Arrival will be early over the North Andaman Sea as well.  It appears that its further advance over Sri Lanka will remain mild and weak. However, the Arabian Sea branch is likely to energise around 25th May 2025. The cross-equatorial flow will pick over the Comorin region and the Maldives and extend to the Lakshadweep Islands (check weather). The southwest monsoon may make a soft landing before the due date of 01st June. There are chances of its earliest arrival since 2009.

The onset of monsoon over the Andaman Sea has no correlation to its further advancement over the mainland region of Kerala (Check Kerala Weather). Yes, as is usually observed, it takes about 10 days for the monsoon stream to travel from North Andaman to Kerala. Further, the onset date of monsoon over Kerala, early or delayed, has no interconnection with its further progress and overall performance in that month or season as a whole. The earliest monsoon arrival since 2009 was on 29th May in 2011, 2018, and 2022. Yes, in 2009, the monsoon arrived on 23rd May, the earliest in the last 15 years. However, the season ended up in a severe drought with seasonal rainfall at 78 % of the long-period average. That also happened to be an El Niño year, which spoiled the monsoon.

Daily Forecast: Weather update and forecast for May 13 across India