MONETABRIEF – Warming of the Western Indian Ocean, known as Indian Ocean Dipole (IOD) Positive phase is likely to bring more rain to Sri Lanka later this year, even as El Niño is likely to intensify to a 75-year record, a top Meterological official said.
When the IOD is in a positive phase in the latter part of the year when Sri Lanka gets the North East monsoon, more water bearing water is drawn over the island from the Bay of Bengal, Director General of the Department of Meteorology, Ajith Wijemannage said.
Towards the end of the year and next year the El Niño phenomenon is expected to intensify to a 75 year high.
An El Niño (Christ Child in Spanish) Southern Oscillation (ENSO) is a condition where surface water in the equatorial Pacific becomes warmer than average and east winds blow weaker than normal.
The opposite condition is called La Niña. During this phase of ENSO, the water is cooler than normal and the east winds are stronger. El Niños takes place every 3 to 5 years.
In most past El Nino events, IOD conditions were positive in relation to Sri Lanka, Wijemannage said.
"In an IOD positive event the Western Indian Ocean becomes warm, creating low pressure and drawing air across the island," he said. "In an IOD negative event the Eastern Indian Ocean becomes warm.
"If the IOD positive event takes place during the South West Monsoon, it can reduce rainfall from that monsoon," Wijemannage.
'If the IOD becomes positive during the North East monsoon, air flows from that areas is enhanced. So more air is drawn across the Bay of Bengal. When the air moves up after hitting there central hills, there is precipitation.
"In the inter-monsoon season if IOD becomes positive air will be drawn across from the Eastern seas with moisture."
Sri Lanka is facing drier than usual conditions after the South West monsoon now, in line with the experience of El Nino in the past.
El Nino tends to make wet seasons wetter and dry seasons drier. The dry season next year from February to April is likely to be wetter and hotter than usual, Wijemannage said.
Though near term predications are more accurate, the Met Department will evaluate emerging data in the future the make firmer predictions regarding next year.
At the moment Sri Lanka is seeing drier than normal weather in several districts in the North, North Central and Easter areas, Environment Minister Dhammika Patabendige said.
Drinking water is being distributed to villagers through bowsers. Though the minor Yala rice harvest is now finished, farmers engaged in other rain fed cultivation are facing crop damage.
To start the main Maha rice cultivation season the island's key reservoirs had 54 percent water storage and others about 36 percent and they will be released. Farmers were urged to start cultivation from October 01. (Colombo/Aug22/2026)