El Nino Watch

ASMC haze alert levels (0-3)

The ASEAN haze centre's alert level for smoke that crosses borders, for the Mekong sub-region (including Thailand) and southern ASEAN: 0 none, 1 dry season, 2 increasing risk, 3 high risk.

Hazards

"Transboundary haze" is smoke from fires that drifts from one country to another. The ASMC issues alert levels for two sub-regions:

  • Mekong sub-region: Myanmar, Thailand, Cambodia, Lao PDR, Vietnam.
  • Southern ASEAN: mainly Sumatra and Kalimantan (Indonesia), which also affects Malaysia, Singapore and southern Thailand.

It weighs forecast rain and winds, smoke haze density, and hotspot counts and locations.

Why it matters for Koh Samui

Samui usually has clean air, but in strong El Nino years haze from Indonesia and Malaysia has reached southern Thailand. A southern ASEAN level 2-3 is a reason to check the air quality factor.

Thresholds

ASMC levelMeaning
0No transboundary smoke haze / stand down
1Dry season
2Increasing risk of transboundary haze (more hotspots, moderate to dense smoke for several days, persistent dry weather, winds towards neighbours)
3High risk of severe transboundary haze (significant persistent hotspots, widespread moderate to dense smoke for several days)

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)