Barometric Pressure Forecast for Koh Samui, Thailand
Barometric pressure forecast for Koh Samui, Thailand — a granite island in the Gulf of Thailand whose wet season runs opposite to the Andaman coast, driven by the northeast monsoon. See current barometric pressure and what it means for weather-sensitive people.
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Pressure and weather in Koh Samui
Koh Samui lies in the Gulf of Thailand off Surat Thani province, a roughly circular island of forested granite hills and coconut plantations fringed by beaches. Its tropical latitude gives it a barometric pressure regime unlike anywhere in the mid-latitudes. The annual range is small, and on most days the largest movement is not weather at all but the semidiurnal atmospheric tide, a twice-daily oscillation of a few hectopascals driven by solar heating of the atmosphere. Near the equator this tide is at its strongest and synoptic variability at its weakest, so the daily rhythm can dominate the trace entirely. The island's seasonal calendar surprises visitors who know Phuket. Sheltered on the gulf side, Samui misses the southwest monsoon that soaks the Andaman coast from May to October, and instead takes its heaviest rain from the northeast monsoon between roughly October and December, when moist air crosses the gulf and piles against the island's hills. That is also when tropical depressions and occasional storms track west out of the South China Sea and across the peninsula, producing the only substantial falls in current barometric pressure the island records. A barometric pressure forecast for Koh Samui matters most from October to December.
What this means for you
Can barometric pressure cause headaches? In the deep tropics the useful thing to understand is that the barometer moves in a regular twice-daily rhythm regardless of the weather, so a small swing is normal rather than significant. The changes worth attending to come with the northeast monsoon and passing depressions. Use this barometric pressure forecast with Pressure Pal as a migraine tracker app and watch pressure change today through the late-year storm season.