Ask anyone in Thailand where the drought is and the answer is Isan. It is the right answer most years, and it is the wrong answer this month. In the drought layer GlobMaps is serving as of 2 September 2026, the province carrying the most severe classification is Phangnga — on the Andaman coast, in a part of the country better known for rainfall than the lack of it.
What the served file actually says
Across all 77 Thai provinces, the served multi-index drought file classifies:
- D4 (exceptional): none
- D3 (extreme): Phangnga
- D2 (severe): Phuket, Prachuap Khiri Khan
Three provinces above the D1 line, and all three are coastal. Two of them — Phangnga and Phuket — sit on the same stretch of Andaman shoreline. Prachuap Khiri Khan is the narrow neck of the Gulf coast. Not one province of the northeast appears.
The provenance, because it changes how much weight this carries
These numbers were read directly off production, not from a summary. The file behind them was last written on 20 August 2026, and the most recent month it covers is July 2026. That gap matters and is worth stating plainly: this is a picture of July, served in September. It is not a statement about the rain that fell last week.
A drought index built on a three-month water balance is designed to move slowly, so a month of lag is normal rather than a defect. But "the driest province right now" and "the driest province in the most recent completed month we have processed" are different claims, and only the second one is supported here.
Malaysia: the wet states are all on the Peninsula
The Malaysian file, written more recently on 29 August, classifies all 16 states and federal territories. Six of them are running wetter than their own historical normal: Johor, Kuala Lumpur, Melaka, Negeri Sembilan, Putrajaya and Selangor.
Every one of those six is on Peninsular Malaysia. The states that come out dry are Kedah, Pulau Pinang — and Sarawak and Labuan, both on Borneo. That inverts the mental shortcut most people carry, in which Borneo means rainforest and the Peninsula means cities and plantations. For a month, the island is the dry half.
The remaining six — Kelantan, Pahang, Perak, Perlis, Sabah and Terengganu — sit at normal.
Why a national average would have hidden all of this
Neither of these findings survives being averaged. Thailand with three coastal provinces above D1 and seventy-four below reads, nationally, as a country with no drought problem. Malaysia with six wet states and four dry ones reads as unremarkable. The signal is entirely in the distribution, and a single national number deletes the distribution by construction.
This is the practical case for province-level resolution, and it is not an abstract one. A lender with exposure concentrated in Phangnga and a lender spread evenly across Thailand face the same national average and completely different weather. Only one of them can see that from a country-level figure, and it is neither.
What this is not
A drought index measures how dry conditions are. It does not measure crop loss, water-supply stress or economic damage, all of which depend on exposure and vulnerability layers that a hazard index does not contain. Phangnga at D3 means the water balance there is unusually negative for the season; it does not, on its own, mean a harvest failed.
Province values are also aggregated from a 31 km reanalysis grid, so small provinces rest on fewer grid cells than large ones and carry more uncertainty per unit area. Phuket is one of the smallest provinces in Thailand. That is a reason to read its classification alongside Phangnga's rather than on its own — which, conveniently, is what the two of them being adjacent already invites.
Province figures read from the GlobMaps production drought layer on 2 September 2026 (vm-inspect run 33623342936). Thailand file written 20 August 2026, latest month covered July 2026; Malaysia file written 29 August 2026. Severity classes are the served multi-index classifications, not a re-derivation.