A calendar label cannot tell you whether a Koh Larn ferry will run or a beach will be suitable on a specific day. Use the current Thai Meteorological Department Chon Buri forecast and shipping forecast, then confirm the operator's sailing status.

Evidence for this passage:Thai Meteorological Department — Chon BuriThai Meteorological Department shipping forecast

TMD's general Thailand framework places the rainy season around mid-May to mid-October, between a hot season around mid-February to mid-May and a cool season around mid-October to mid-February. TMD also notes that seasonal onset can vary. This national framework is orientation only—not a Koh Larn forecast, sea-state promise or best-month recommendation.

Evidence for this passage:Thai Meteorological Department — Thailand seasonal framework

What to check for the actual date#

The registered sources for this guide are TMD's current Chon Buri and shipping forecasts. This article does not turn national season dates or mainland station normals into a Koh Larn condition claim; read the live forecasts for the actual travel day.

How to play it#

  • Read the TMD Chon Buri forecast and shipping forecast close to departure.
  • Confirm the operator's sailing status; a regional warning does not by itself prove a cancellation.
  • Keep a mainland alternative if the sea state, warning flags or operator advice make the crossing unsuitable.
  • Follow any beach warning and use the DMCR first-aid protocol if a dangerous-jellyfish sting is suspected.

Evidence for this passage:Thai Meteorological Department — Chon BuriThai Meteorological Department shipping forecastDepartment of Marine and Coastal Resources jellyfish guidance

What the calendar cannot settle#

Rainy-season conditions and demand vary by day. A lower-demand date may provide more space, but neither water clarity nor operating schedules can be inferred from the calendar alone.

Tip: A safer decision rule is to check the current TMD provincial forecast, the shipping warning and the operator's sailing status before leaving Pattaya. A regional warning does not itself prove a cancellation; confirm with the operator.

For the current official weather links and the sourced dangerous-jellyfish first-aid protocol, see the practical guide.