Thailand Monsoon Season Weather Checker

Stop guessing Thailand’s monsoon—decide when to go: Go / Iffy / Avoid for any month

Pick a destination and month to get a quick Go / Iffy / Avoid signal based on historical climate normals (1991–2020) from Thailand’s Meteorological Department (TMD). You’ll also see average rainfall, rainy days, temperature, and a one-line sea conditions note for island/coastal areas. No forecasts — purely historical patterns.

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Frequently Asked Questions

Below are the most common questions travelers have about Thailand’s monsoon patterns—how to read Go / Iffy / Avoid, coast-by-coast seasonality, and when ferries can be affected.

📌 How are the ratings decided?

We use TMD (Thailand’s Meteorological Department) 1991–2020 monthly averages for rainfall (mm) and rainy days.

• Go: < 150 mm and < 10 rainy days
• Iffy: 150–300 mm or 10–15 rainy days
• Avoid: > 300 mm or > 15 rainy days

Islands/coasts are downgraded one level in typical rough-sea windows: Andaman (May–Oct), Gulf east (Oct–Jan), Eastern seaboard/Trat (Sep–Jan), Upper Gulf west (Sep–Nov). Not a forecast—historical norms only.

📌 Why is an island “Iffy” in a drier month?

Sea-state adjustment. Example: Koh Chang in December has relatively low rain, but it sits inside the Trat/eastern seaboard rough-sea window, so Go → Iffy.

📌 Does this show forecasts?

No. It uses TMD 1991–2020 climate normals only. Always check a short-range forecast and marine advisories near your dates.

📌 Where does the data come from?

Thai Meteorological Department (TMD) 30-year normals (1991–2020). Major destinations use station-level normals; others use regional proxies (shown under “Data source”).

📌 Why is Samui OK in June but Phuket isn’t?

Different monsoons. The SW monsoon makes the Andaman (Phuket/Krabi) wetter May–Oct, while the NE monsoon peaks on the Gulf east (Samui/Phangan/Tao) roughly Oct–Jan.

📌 Does “200 mm” mean it rains all day?

Not necessarily. The tropics often see short, heavy bursts. The mm figure is the monthly total; rainy days hints at how frequently showers occur.

📌 Are ferries reliable during monsoon months?

They usually run but can be delayed or cancelled in rough seas. Build slack into travel days and check operators the day before.

📌 Does this include waves, dive visibility, or wind?

No—only rain/temperature norms plus a simple sea note. For marine specifics, check local marine forecasts and dive operators.

📌 What about air quality in the north?

Air quality (smoke/haze) isn’t part of this tool. If you’re considering Chiang Mai/Chiang Rai in late Feb–Apr, check current AQI sources.

📌 My place isn’t listed—what should I pick?

Choose the nearest listed destination or the matching region (e.g., Andaman, Gulf east). The Data source line shows if it’s a regional proxy.

📌 Why did the tool suggest another coast?

When a month is Avoid (or Iffy) for one coast, the other coast or an inland spot often has better historical odds. The suggestions reflect that seasonal complement.

📌 Can I share a specific combo?

Yes—use Copy link to share a deep link like ?dest=Phuket&month=January.

📌 Is this precise for every beach on an island?

Microclimates vary. The tool reflects station/region averages—great for planning, but not a guarantee for a specific bay or day.

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Link to This Free Thailand Monsoon Weather Checker

Run a travel blog, island guide, or Thailand planning site? Your readers will love this tool—it gives a clear Go / Iffy / Avoid for any destination + month, using TMD 1991–2020 historical normals (no forecasts).

📌 Why link to this page?

• Adds value to your content (instant, trustworthy guidance—rainfall, rainy days, temps, and a sea note)
• Easy to share — deep link to exact states (e.g., ?dest=Phuket&month=January); the page also has a Copy link button
• Completely free and kept up to date with historical data sources

✅ Tip for bloggers: link directly to the destination you mention in an article, e.g.
/thailand-monsoon-season-weather-checker/?dest=Koh%20Samui&month=June (Samui in June)
/thailand-monsoon-season-weather-checker/?dest=Phuket&month=January (Phuket in January)