Marine Weather API for Southeast Asia

Marine Weather Challenges in Southeast Asia

Southeast Asia spans from Thailand and Myanmar through Malaysia, Indonesia, Philippines, and Vietnam — thousands of islands and millions of square kilometers of ocean. The region hosts some of the world's busiest shipping lanes, a massive dive and liveaboard industry, and island-hopping tourism that depends entirely on marine conditions.

The monsoon system dominates marine planning across the region. The southwest monsoon (May–October) brings rough seas to Thailand's west coast and the Andaman Sea while the east coast stays calm, and the pattern reverses during the northeast monsoon (November–March). Understanding which monsoon is active is the single most important factor for marine operations.

Dive and liveaboard operations are a massive industry throughout Southeast Asia. Thailand, Indonesia (Raja Ampat, Komodo), and the Philippines (Palawan) all depend on accurate marine forecasts to plan safe and enjoyable trips through some of the world's most biodiverse waters.

The Strait of Malacca carries roughly 25% of global trade — weather affects shipping efficiency and crew safety for the thousands of vessels transiting this narrow waterway every day.

Get a Marine Forecast for Southeast Asia

Here's how to get an AI-powered marine weather forecast for Phuket, Thailand — one of Southeast Asia's most popular dive and boating destinations:

curl -X POST https://api.sealegs.ai/v3/spotcast \
  -H "X-API-Key: your_api_key" \
  -d '{
    "latitude": 8.0863,
    "longitude": 98.9063,
    "start_date": "2026-01-20",
    "num_days": 3,
    "vessel_info": {
      "type": "diving",
      "length_ft": 65
    }
  }'

{
  "summary": "Ideal conditions for a 65ft dive vessel off Phuket.
    Light easterly winds 8-12kt during the northeast monsoon
    season — the west coast (Andaman Sea) is calm and clear.
    Seas 1-2ft with a long 10-second period from distant Indian
    Ocean swell. Excellent visibility expected. Perfect conditions
    for dive operations at the Similan Islands.",
  "daily_forecasts": [
    {
      "date": "2026-01-20",
      "classification": "Excellent",
      "confidence": 0.92,
      "wind_speed_kt": 10,
      "wind_gust_kt": 14,
      "wave_height_ft": 1.5,
      "wave_period_s": 10
    }
  ]
}

The same request works for any Southeast Asian coordinates. Use 9.5120, 100.0136 for Koh Samui, -8.3405, 115.0920 for Bali, or 9.8349, 118.7384 for Palawan.

Key Weather Parameters for Southeast Asia

The API returns a full set of marine weather parameters. For Southeast Asian waters, these are especially important:

• Wind speed & direction — Monsoon direction is THE key factor; it determines which coasts are diveable, sailable, and accessible throughout the region
• Wave height & period — Indian Ocean swell affects Thailand's west coast; South China Sea conditions affect east coast and Philippine waters
• Visibility — Essential for dive operations; varies dramatically between monsoon seasons and can make or break a dive trip
• Precipitation — Heavy tropical rain squalls affect navigation and passenger comfort, especially during monsoon transitions
• AI classification — The daily GO / CAUTION / NO-GO rating accounts for how all parameters interact for your vessel type

Use Cases in Southeast Asia

Popular Southeast Asia Coordinates

Here are commonly used coordinates for Southeast Asian marine forecasts:

• Phuket, Thailand — 8.0863, 98.9063
• Koh Samui, Thailand — 9.5120, 100.0136
• Bali, Indonesia — -8.3405, 115.0920
• Singapore Strait — 1.2580, 103.8198
• Palawan, Philippines — 9.8349, 118.7384
• Halong Bay, Vietnam — 20.9101, 107.1839