SUSTAINABILITY · 7 min read
The Met Department Issued a Seven-Month Forecast for Sri Lanka. The Coverage Kept Ten Days of It
On 16 September, the Director General of Meteorology set out conditions running to April 2027 and closed by asking the country to manage the water it is about to receive. Every account of the briefing focused on the ten-day outlook. The evidence behind the part that was left out is stronger than the evidence behind the part that ran.
By the ESGNexus Editorial Team · September 2026 · Estimated reading time: 7 minutes
KEY TAKEAWAYS
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Ajith Wijemanna spent part of his media conference on 16 September on the next ten days. He spent the rest of it on the next seven months. The ten days made every headline. The seven months did not.
That is the whole problem with how this season is being explained to the public. The country is being prepared for water, when what it needs to prepare for is water, followed by its absence.
What the Director General Actually Said
The near-term warning was clear enough. Widespread rain across the island within ten days, with heavy falls, landslides and flooding all possible. Then, in October and November, disturbances form in the Bay of Bengal and could be intensified by El Niño. Then December, with rainfall rising in the north-east. Northern and Eastern provinces were given an average rainfall forecast, with the caveat that certain Indian Ocean Dipole conditions could still cause flooding.
Then the part that travelled no further than the closing paragraphs. February, March and April next year: higher temperatures, and relatively lower rainfall. The Ada Derana account adds one more line, which no other outlet carried. The Director General stressed the importance of properly managing the rainfall the country receives over the coming months.
Read the two halves together, and the briefing stops being a flood warning. It becomes an instruction about storage.
| Period | What the Department Said on 16 September | What the Published Evidence Adds |
| Now to late September | Widespread rain within ten days; heavy falls, landslides and flooding possible | Reservoirs stood at 47.3 per cent nationally on 7 September, with major reservoirs at 34.4 per cent |
| October to November | Heavy rainfall; Bay of Bengal disturbances that ElNiñoo could intensify | El Niño raises rainfall in the first three months of the Maha season; this is the better-established half of the signal |
| December | Rainfall increasing in the north-east | A positive Indian Ocean Dipole was forecast to develop from September, which pushes the same way |
| January to March 2027 | Not addressed directly in the accounts of the briefing | The same work finds rainfall falling in the last three months of Maha — a reversal within one season |
| February to April 2027 | Higher temperatures and relatively lower rainfall | In 1983, 1998 and 2016, between 95 and 99 per cent of Sri Lankan stations recorded a drier first inter-monsoon |
Sources: Ada Derana and Newswire reports of the Department of Meteorology media conference, 16 September 2026; De Silva and Hornberger, Hydrology and Earth System Sciences, 2019; Ranaweera and Kamae, Frontiers in Climate, 2024; Irrigation Department figures for 7 September 2026 as reported.
The Department’s Own Published Note Stops in September
The El Niño update linked from the Department of Meteorology’s homepage is numbered DoM/Awareness/02-2026 and dated 3 July 2026. Its monthly rainfall tables cover July, August and September. There is nothing in it for October or any month after.
That note was sound when it was written. It put the chance of a very strong El Niño developing between November and January at 63 per cent, and it warned that rainfall from October onward could bring floods and landslides. Ten weeks later, the forcing has moved a long way. The US Climate Prediction Centre’s 10 September discussion opens with the line that El Niño is strengthening, with a greater than 90 per cent chance of a very strong event through the northern hemisphere autumn and winter. It puts the odds at 75 per cent that October to December produces a historic event stronger than any since 1950. The August Niño-3.4 reading was plus 1.8 degrees.
Checking meteo.gov.lk on 17 September, ESGNexus could not find a published departmental forecast covering October 2026 onward. That is a statement about what a check on one date found, not a claim about what the Department has produced. If such a document exists on a page the check missed, or circulates to agencies without being posted, ESGNexus will say so. The point stands either way: the public heard a seven-month outlook stated at a press conference and has no published document to hold it to.
Why the Rain Is Not the End of the Drought
When the rain arrives in October, it will be a relief for ministers, boards,s and farmers alike, as the drought breaks. The published work on Sri Lankan rainfall says something narrower and less comfortable.
De Silva and Hornberger, working with sub-basin rainfall records, found that El Niño increases rainfall in the first three months of the Maha season and decreases it in the last three. The reversal happens within a single growing season. Wet October to December, dry January to March. Their classification models achieved 65 to 84 per cent accuracy in drought prediction across eight sub-basins, which they themselves describe as modest.
The back half has since been measured more precisely. Lin and colleagues, writing this year, find a significant negative relationship between ENSO and January-to-April rainfall over southern India and Sri Lanka, and note that this relationship has been strengthening. Before the late 1970s, the correlation was statistically insignificant. From 1985 to 2024, it clears the 99% significance level. Ranaweera and Kamae looked specifically at the first inter-monsoon of the year following an El Niño. In all three super events on record, 1982-83, 1997-98 and 2015-16, between 95 and 99 per cent of Sri Lankan stations were drier in the following March and April.
One event ran the other way. The 1987-88 El Niño was followed by a wetter first inter-monsoon at 87 per cent of stations, and the authors attribute that to how quickly conditions flipped to La Niña. It is a real exception, and it is worth holding on to, because it is the reason none of this is certain. But a pattern that holds in three of four strong cases, and in three of three super cases, is not something to plan around ignoring.
| What the Evidence Says | How It Was Measured | Source |
| ElNiñoo raises Sri Lankan rainfall in October to December and lowers it in January to March | Sub-basin rainfall records and classification models; drought models 65 to 84 per cent accurate across eight sub-basins | De Silva and Hornberger, Hydrology and Earth System Sciences, 2019 |
| The ENSO link to January-April rainfall is negative and has strengthened since the 1980s | Insignificant for 1950 to 1979; above the 99 per cent significance level for 1985 to 2024 | Lin, Zhuang, Yang and Wang, Atmosphere, 2026 |
| The first inter-monsoon after a super El Niño is drier almost everywhere | 95 to 99 per cent of stations drier in March and April of 1983, 1998 and 2016; one strong event in 1988 ran the other way | Ranaweera and Kamae, Frontiers in Climate, 2024 |
| The December to February response to El Niño is suppressive, not additive | Observations and reanalysis, 1981 to 2022; driven by an anticyclone over the Bay of Bengal | Kajakokulan, Santoso and Zhao, Climate Dynamics, 2025 |
Reading these four together: the wet signal and the dry signal are not in conflict. The first sits in the second inter-monsoon, October to December. The second sits in the months after it. That synthesis is ours, not a claim made by any single paper.
The Slopes Are Not the Ones That Were There Last Year
Cyclone Ditwah killed 646 people in late 2025, with 173 still recorded as missing. It touched all 25 districts and about 2.2 million people. Nearly 6,000 houses were destroyed outright and more than 108,000 were partially damaged. The United Nations situation report of 23 January called it the most extensive flooding and landslide damage Sri Lanka had seen in two decades.
A partially damaged house is the category that matters here. It is the one that gets patched rather than rebuilt, stays occupied during the repair, and meets the next season with a weakened roof or a cracked retaining wall. There are more than 100,000 of them.
On the same day as the Met briefing, NBRO put more than 30,000 families at risk of landslides following Ditwah, and made the point that areas previously considered safe may no longer be. Neither account of that warning names an official, so it stands as an institutional statement rather than a quoted one. The substance is not complicated. Water reshaped those slopes last year, and the maps drawn before it no longer describe them.
| Sri Lanka’s current early warning system is fragmented and not trusted enough. — Professor Dilanthi Amaratunga, Loughborough University |
That assessment was based on research on the Ditwah response published in Progress in Disaster Science. The study found that warnings were confusing and inconsistent, issued in a limited set of languages, with different agencies issuing their own messages separately. It also found that funding had gone to recovery rather than to prevention, and that local authorities lacked the capacity to enforce safe planning. Ten months on, the same window is opening under a stronger forcing, and there is no public evidence that the warning problem has been fixed.
What the Next Six Weeks Decide
For any organisation reporting under SLFRS S2, this is not a weather story. It is a named, dated, quantified physical risk occurring within the current reporting year, with an official probability attached. A climate risk section that describes exposure in general terms while this sits in the forecast is going to read badly in twelve months.
The practical question is narrower than scenario analysis and concerns storage rather than defence. Reservoirs were at 47.3 per cent nationally on 7 September, major reservoirs at 34.4 per cent, and eastern districts at roughly a fifth. Those are the Irrigation Department’s reported figures, and the three scopes matter because the headline number is the kindest of the three. Between October and December those reservoirs will refill. What happens after April depends almost entirely on how much of that water is still there — which is the point the Director General made at the end of his briefing, and the one that did not get printed.
The same logic runs through a factory water balance, a plantation’s storage tanks, a hotel’s borehole and a bank’s agricultural loan book. Everyone gets more water than they can use for about ten weeks. Most of them have nowhere to put it.
What to Do Now
1. Treat October to December as a filling season, not a wet season. Tank capacity, roof catchment, bund repairs and desilting are worth more now than at any point in the next year. Anything installed before the rain arrives works for the whole of it.
2. Check the ground you are standing on, not the map of it. If your home, estate or site is in or near an area Ditwah touched, the slope behind it may have changed. NBRO’s district warnings are the reference, and its point that safe areas may no longer be safe applies to properties that came through intact last year.
3. Plan the dry half before the wet half arrives. February to April is when water restrictions, higher thermal generation costs, and crop stress converge. Contracts, tariffs and covenants that get reviewed in January are easier to move in October.
4. Write the physical risk down while it is still a forecast. For SLFRS S2 reporters, a climate risk disclosure drafted against a previously published forecast is worth considerably more than one reconstructed afterwards. The dates and probabilities are all on the public record.
5. For households, prepare for two things, not one. The first is the obvious one: documents in a waterproof bag, a torch and a radio, an agreed meeting place, and a plan that does not depend on a phone network. The second is less obvious and costs almost nothing: store water during the months when there is too much of it, because the months when there is not enough are already on the forecast.
What We Will Be Watching
Three things between now and the new year. Whether the Department publishes a written seasonal outlook covering October to April, which would give the public something to hold the spoken forecast to. Whether the reservoir figures released in the season report are presented by scope rather than as a single national percentage, a distinction ESGNexus has tracked since August. And whether the physical risk sections of the December and March filings name this season at all. ESGNexus will come back to the third of those when the filings land.
Sources & Further Reading
Ada Derana, “Sri Lanka to experience widespread rainfall in the next 10 days: Met. Dept.”, 16 September 2026 — adaderana.lk
Daily Mirror, “Widespread rain expected across Sri Lanka over next 10 days”, 16 September 2026 — dailymirror.lk
Newswire, “El Nino: Rainfall expected across Sri Lanka over next 10 days”, 16 September 2026 — newswire.lk
Department of Meteorology, “El Niño Updates”, DoM/Awareness/02-2026, 3 July 2026 — meteo.gov.lk
NOAA Climate Prediction Centre, “ENSO Diagnostic Discussion”, 10 September 2026 — cpc.ncep.noaa.gov
De Silva, M. M. G. T. and Hornberger, G. M., “Identifying El Niño-Southern Oscillation influences on rainfall with classification models: implications for water resource management of Sri Lanka”, Hydrology and Earth System Sciences 23, 2019 — hess.copernicus.org
Lin, Zhuang, Yang and Wang, “Strengthened ENSO Impact on January-April Rainfall over Southern India and Sri Lanka in Recent Decades”, Atmosphere 17(3), 2026 — mdpi.com
Ranaweera and Kamae, “Impact of El Niño Southern Oscillation on the first inter-monsoon rainfall over Sri Lanka in the post-El Niño years”, Frontiers in Climate 6, 2024 — frontiersin.org
Kajakokulan, Santoso and Zhao, “Asymmetric response of Sri Lanka Northeast Monsoon rainfall to El Nino/La Nina”, Climate Dynamics 63, 2025 — link.springer.com
OCHA and UN Resident Coordinator’s Office, “Cyclone Ditwah Situation Report”, 23 January 2026 — srilanka.un.org
Daily Mirror, “30,000 families at risk of landslides after cyclone Ditwah”, 16 September 2026 — dailymirror.lk
Loughborough University, “Weakness in Sri Lanka’s planning led to increased damage after Cyclone Ditwah, research finds”, February 2026, published in Progress in Disaster Science — lboro.ac.uk
FAO, WFP, UN Women, WMO and OCHA, “Asia and the Pacific: Snapshot of El Niño, Indian Ocean Dipole and Middle East Crisis”, 28 August 2026 — srilanka.un.org
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