El Nino Watch

Koh Samui risk levels (0-4)

One overall level for the island, from 0 Normal to 4 Leave, computed from 9 factors with documented rules. Each factor shows its value, threshold and source.

Koh Samui watch

The Samui page turns many numbers into one answer: how worried should you be, and what should you do now?

How it works, in short:

  • 9 factors are scored from 0 to 4 each: El Nino, water, heat, flood, cyclone/wind, sea state, air quality, marine heat and news. See The 9 risk factors.
  • 4 rules combine them into one overall level. See How the overall level is decided (rules R1-R4).
  • If a critical factor has no current data, the level becomes Unknown, never "Normal". See Data coverage.

Every factor shows its value, the threshold that applies, the explanation, the source and the time of the data. Nothing is hidden in a black-box score.

Why it matters for Koh Samui

The level is a planning aid, not an official warning. When Thai authorities (TMD, DDPM, the province) issue orders, follow them first.

Thresholds

LevelNameMeansWhat to do (summary)
0NormalNothing abnormal expected on the island.Keep a basic 3-day stock; review the Preparedness page once a month.
1WatchSomething is building up somewhere (El Nino, a rain deficit, a distant storm).Check the page daily, follow TMD warnings, build 7 days of drinking water, note ferry and airport contacts.
2PrepareA real hazard is likely in the coming days or season.Build 14 days of self-sufficiency, fill the cistern, charge batteries, copy documents, decide your departure threshold.
3ActA hazard is here or imminent, or two hazards combine.Apply the matching scenario, stock water and fuel, pack the go-bag, check ferries and flights every morning.
4LeaveSafety or basic supplies are directly threatened.Leave while ferries and flights run, or follow the authorities (DDPM 1784).

Full action lists are on the Learn page ("What to do at each level") and on the Samui page. The engine calls level 1 "vigilance" internally; it is shown as Watch.

Sources

Related

ENSO status now

ONI (NOAA CPC)
+1.80 °C, JJA 2026 (previous +1.39 °C)
RONI (NOAA CPC)
+1.36 °C, JJA 2026
Nino 3.4 weekly (NOAA CPC / OISST)
+3.0 °C anomaly, week of 16 Sep 2026 (SST 29.6 °C)