El Nino Watch

Factor: tropical cyclone / wind

Looks for GDACS tropical cyclones by distance to Samui and by alert colour, plus forecast wind gusts for 72 h and TMD storm warnings.

Koh Samui watch

The factor takes the highest of:

  • The cyclone level (table below), from GDACS cyclone positions and colours.
  • The gust level, from the strongest forecast gust in the next 72 hours (Beaufort scale; Samui often sees 55-70 km/h gusts in the monsoons, so it starts at strong gale).
  • A TMD storm warning in force: at least 2.

If neither GDACS nor the TMD has answered recently, the factor is unknown: a cyclone cannot be ruled out.

Why it matters for Koh Samui

Cyclones are rare on Samui but destructive (Harriet 1962, Gay 1989, Pabuk January 2019). They mostly arrive from October to January.

Thresholds

ConditionFactor level
Any GDACS cyclone within 800 km1 Watch
Orange/red cyclone within 800 km2 Prepare
Any cyclone within 300 km3 Act
Orange/red cyclone within 300 km4 Leave (rule R4a)
Gusts 75-88 km/h (Beaufort 9)1 Watch
Gusts 89-117 km/h (Beaufort 10-11)2 Prepare
Gusts 118 km/h or more (Beaufort 12)3 Act

Cap: 3, except the orange/red cyclone within 300 km, which sets the overall level to 4. Critical factor.

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)