| Month | Mean, °C | Mean max, °C | Mean min, °C | Rain, mm | Rain days | Humidity, % |
|---|---|---|---|---|---|---|
| January | 27.7 | 32.6 | 24.1 | 31.0 | 3.9 | 76 |
| February | 28.3 | 33.5 | 24.4 | 24.1 | 2.2 | 74 |
| March | 28.8 | 33.9 | 24.7 | 69.0 | 5.6 | 77 |
| April | 29.0 | 33.8 | 25.1 | 121.6 | 10.4 | 80 |
| May | 28.9 | 32.6 | 25.4 | 227.5 | 16.7 | 83 |
| June | 28.5 | 31.9 | 25.3 | 285.9 | 16.7 | 83 |
| July | 28.2 | 31.6 | 25.1 | 288.5 | 16.7 | 83 |
| August | 28.2 | 31.2 | 25.2 | 342.0 | 17.0 | 83 |
| September | 27.8 | 30.9 | 24.8 | 319.4 | 19.0 | 85 |
| October | 27.4 | 31.0 | 24.5 | 297.5 | 20.2 | 86 |
| November | 27.2 | 31.3 | 24.3 | 148.4 | 14.8 | 84 |
| December | 27.1 | 31.4 | 23.9 | 64.6 | 9.6 | 80 |
| Year | 28.1 | 32.1 | 24.7 | 2,219.5 | 152.8 | 81 |
The table above is a climate normal: averages over 30 years, not a forecast for any given year. A single year can be drier or wetter. For planning a trip, the normal is more useful than last year’s weather: it shows what to expect in a typical month.
What the numbers show
Temperature barely changes. The warmest month (April, 29.0 °C) and the coolest (December, 27.1 °C) are under 2 degrees apart. Nights stay at 23.9-25.4 °C on average all year.
Rain sets the seasons, and the dry season is deep. From December to March 24-69 mm falls each month, with 2-10 rain days. From May to October it is 228-342 mm and 17-20 rain days. February has fewer rain days on Koh Lanta (2.2) than at the Krabi (4.3) and Phuket town (3.4) stations. A rain day means at least 0.1 mm, so short showers count too.
Humidity follows the rain: from 74% in February to 86% in October.
Koh Lanta weather by season
Our grouping of the monthly TMD figures in the table above (Ko Lanta station, 1991-2020).
| Period | Months | Mean max, °C | Rain a month, mm | Rain days a month | Humidity, % |
|---|---|---|---|---|---|
| Dry | December-March | 31.4-33.9 | 24.1-69.0 | 2.2-9.6 | 74-80 |
| Warmest on average | April | 33.8 | 121.6 | 10.4 | 80 |
| Rainy | May-October | 30.9-32.6 | 227.5-342.0 | 16.7-20.2 | 83-86 |
| Transition | November | 31.3 | 148.4 | 14.8 | 84 |
TMD describes the country’s seasons this way: the north-east monsoon blows from October to February and brings mostly dry weather, February to May is the hot transition, and the south-west monsoon from May to October brings moisture from the ocean, with the heaviest rain on coasts and windward slopes. Koh Lanta faces the Andaman Sea. At the station westerly winds dominate from April to October, and from May to September the mean wind speed is 4.8-7.3 knots, against 2.6-3.8 knots from November to March.
The same month across the country: Thailand in November, Thailand in December.
Koh Lanta, Krabi and Phuket compared
Annual figures from the same TMD report. The Ko Lanta station is about 64 km from the Krabi station (our calculation from the coordinates in the report).
| Annual figure | Ko Lanta (48 566) | Krabi (48 563) | Phuket town (48 564) |
|---|---|---|---|
| Mean temperature | 28.1 °C | 27.6 °C | 28.5 °C |
| Mean minimum | 24.7 °C | 22.4 °C | 25.5 °C |
| Rainfall | 2,219.5 mm | 2,180.7 mm | 2,271.5 mm |
| Rain days | 152.8 | 172.2 | 174.9 |
| Thunderstorm days | 20.6 | 51.5 | 43.6 |
| Driest month | February, 24.1 mm | February, 35.9 mm | February, 24.0 mm |
| Wettest month | August, 342.0 mm | October, 292.9 mm | September, 350.4 mm |
| Period | 1991-2020 | 1994-2020 | 1991-2020 |
Koh Lanta has the fewest rain days of the three, about 20 fewer a year than Krabi or Phuket town, and less than half as many days with thunder. Month by month: Krabi weather, Phuket weather.
Where the station is
The TMD station is called Ko Lanta, at 07°32’ N, 99°03’ E and 2 m above sea level according to the report. The coordinates are given to the nearest minute, an error of about 1-2 km, so we do not tie it to a particular beach. For Klong Dao, Long Beach or Kantiang this is a guide, not a measurement on the beach.
Today’s forecast from TMD
The normals show a typical month, not the coming week. For the next seven days use the TMD 7-day forecast: it is given by region, and Koh Lanta is on the Andaman side of the south, Southern (West Coast).
Method and limits
- Source: Thai Meteorological Department report Climatological Data of Thailand for 30 Year Period (1991-2020), 2023 edition, printed page 84 (Ko Lanta). The report is published on a TMD subdomain.
- Period: 30 years, 1991-2020, the latest 30-year period for which TMD has published normals.
- How we compiled it: figures copied from the report without recalculation. We checked monthly totals against the annual values and found no discrepancies.
- Rain day: at least 0.1 mm in 24 hours, counted from 07:00 to 07:00
- What is missing: sunshine hours, sea temperature and waves. The report shows no sunshine observations for the Ko Lanta station, and we found no primary normals for sea temperature or wave height off the island.
- Next update: when TMD publishes new normals or at our April 2027 review
Who Koh Lanta suits, its beaches and how to get there: Koh Lanta area guide.
FAQ
What is the best month for weather on Koh Lanta?
By the TMD normals, February: the driest month with 24.1 mm of rain and only 2.2 rain days, highs of 33.5 °C and the lowest humidity of the year, 74%. January is almost as dry, with 31.0 mm and 3.9 rain days. The normals do not cover waves or sea temperature.
When is the rainy season on Koh Lanta?
According to the Thai Meteorological Department, the south-west monsoon that brings the rain blows from May to October. On Koh Lanta those months get 227.5-342.0 mm each, with 16.7-20.2 rain days. August is the wettest month, October has the most rain days.
When is the dry season on Koh Lanta?
December to March: 24.1-69.0 mm of rain a month on the TMD normals, with rain days ranging from 2.2 in February to 9.6 in December. April is hotter and wetter, 121.6 mm. The south-west monsoon arrives in May.
What is the hottest month on Koh Lanta?
April: a mean of 29.0 °C and an average high of 33.8 °C. March has a slightly higher average maximum, 33.9 °C, and the station's record high over 1991-2020, 38.5 °C, was in April.
What is the weather like on Koh Lanta in November?
November is a transition month: rainfall halves compared with October (148.4 mm against 297.5) and there are 14.8 rain days. Highs are around 31.3 °C, nights around 24.3 °C. The dry weather settles in from December.
What is the weather like on Koh Lanta in December?
December is the first dry month: 64.6 mm of rain and 9.6 rain days on average, highs of 31.4 °C and nights around 23.9 °C. January and February are drier still, with 31.0 and 24.1 mm.
Is Koh Lanta drier than Krabi and Phuket?
In the dry season, yes. From December to March the Ko Lanta station gets 24.1-69.0 mm a month, against 35.9-108.4 mm at Krabi and 24.0-82.0 mm in Phuket town. Over a whole year the totals are close: 2,219.5 mm on Koh Lanta, 2,180.7 mm at Krabi and 2,271.5 mm in Phuket town.
Is it windier on Koh Lanta in the rainy season?
At the station, yes. The mean wind speed is 4.8-7.3 knots from May to September and 2.6-3.8 knots from November to March. From April to October the wind blows mostly from the west, from November to February from the north-east. The normals do not include wave height.
Sources
- Thai Meteorological Department. Climatological Data of Thailand for 30 Year Period (1991-2020), printed pages 82 (Phuket), 84 (Ko Lanta) and 85 (Krabi)
- Thai Meteorological Department. Natural hazards in Thailand: climate and seasons, pages 2-3 (Thai)
- Thai Meteorological Department. 7-day weather forecast (regions)
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