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Best time to visit Ko Samui

The best time to visit Ko Samui is January–February, judged on twenty years of weather records and the events worth going for.

Ko Samui, Surat Thani, Thailand

°C

mm

−10°0°10°20°30°40°
0100200300400500
  • Average daily high and low
  • Precipitation
  • Good month
  • Best month
  • Made good or best by an event
Average daily high and low temperature, average precipitation and each month's verdict
MonthAverage daily highAverage daily lowPrecipitationVerdict
January27.2 °C / 81 °F26 °C / 79 °F85 mm / 3.4 inbest month
February27.5 °C / 82 °F26.4 °C / 80 °F44 mm / 1.7 inbest month
March28.2 °C / 83 °F27 °C / 81 °F84 mm / 3.3 ingood month
April29.1 °C / 84 °F27.6 °C / 82 °F118 mm / 4.7 inneither best nor good
May29.5 °C / 85 °F27.6 °C / 82 °F127 mm / 5 inneither best nor good
June29.5 °C / 85 °F27.5 °C / 82 °F79 mm / 3.1 ingood month
July29.1 °C / 84 °F27.2 °C / 81 °F86 mm / 3.4 ingood month
August28.9 °C / 84 °F27.1 °C / 81 °F81 mm / 3.2 ingood month
September28.5 °C / 83 °F26.8 °C / 80 °F142 mm / 5.6 inneither best nor good
October28 °C / 82 °F26.3 °C / 79 °F250 mm / 9.8 inneither best nor good
November27.9 °C / 82 °F26.3 °C / 79 °F314 mm / 12.4 inneither best nor good
December27.5 °C / 82 °F26.2 °C / 79 °F160 mm / 6.3 inneither best nor good
Good and best months depend on more than temperature, rain and events. How they are chosen

Each activity on this page has its own good and best months, rated on twenty years of daily weather records. Which measures count, and how much, depends on the activity: humidity for exploring outdoors, wind for the beach, hiking and skiing, snow for skiing alone. Between them, the activities are rated on:

  • Daytime highs
  • Night-time lows
  • How warm it feels
  • Humidity
  • How much of the day is sunny
  • Hours of daylight
  • Monthly rainfall
  • How many days it rains
  • Days of heavy rain
  • Wind
  • Snowfall and days with snow
  • Major events, such as festivals

The chart shows the good and best months for exploring outdoors.

The event icon marks a month that an event lifts to good or best, such as a festival or a natural spectacle. Choose “Weather only” in the toolbar to rate the months on weather alone.

Best months by activity

Exploring outdoors

Mild days and nights, mostly dry and bright. The default for 'when should I go'.

  1. JJanuary: best
  2. FFebruary: best
  3. MMarch: good
  4. AApril: neither
  5. MMay: neither
  6. JJune: good
  7. JJuly: good
  8. AAugust: good
  9. SSeptember: neither
  10. OOctober: neither
  11. NNovember: neither
  12. DDecember: neither
Best
January–February
Good
March, June–August

Ko Samui is warm and humid year-round so no month is ever truly mild for exploring, but January, February and June through August are driest with only light, low-intensity rain; March is a hotter but still good option, while April, May and the heavy monsoon stretch from September through December bring too much heat, humidity or heavy rain for comfortable walking.

Why these months

  • January · best

    In its favour: share of daylight that is sunny 89%, average daily high 27.2 °C / 81 °F, precipitation 85 mm / 3.4 in, days with heavy rain 2 days, wet days 9.7 days.

    Against: relative humidity 78%, feels like (high) 30.8 °C / 87 °F, average daily low 26 °C / 79 °F.

    Also on: Buffalo Fighting Festival.

    Watch out for: Chinese New Year travel rush, Christmas and New Year's travel rush.

  • February · best

    In its favour: precipitation 44 mm / 1.7 in, share of daylight that is sunny 91%, average daily high 27.5 °C / 82 °F, days with heavy rain 1.1 days, wet days 6.7 days.

    Against: relative humidity 78%, feels like (high) 31.6 °C / 89 °F, average daily low 26.4 °C / 80 °F.

    Also on: Makha Bucha.

    Watch out for: Chinese New Year travel rush.

  • March · good

    In its favour: share of daylight that is sunny 90%, precipitation 84 mm / 3.3 in, average daily high 28.2 °C / 83 °F, days with heavy rain 1.7 days, wet days 8.4 days.

    Against: feels like (high) 33.5 °C / 92 °F, relative humidity 79%, average daily low 27 °C / 81 °F.

    Also on: Ko Samui Midnight Run, Makha Bucha, Whale shark encounters at Sail Rock.

  • June · good

    In its favour: share of daylight that is sunny 80%, precipitation 79 mm / 3.1 in, days with heavy rain 1.4 days, average daily high 29.5 °C / 85 °F.

    Against: feels like (high) 34.5 °C / 94 °F, wet days 17.1 days, relative humidity 78%, average daily low 27.5 °C / 82 °F.

  • July · good

    In its favour: share of daylight that is sunny 75%, precipitation 86 mm / 3.4 in, days with heavy rain 2 days, average daily high 29.1 °C / 84 °F.

    Against: feels like (high) 33.7 °C / 93 °F, wet days 18.1 days, relative humidity 79%, average daily low 27.2 °C / 81 °F.

    Also on: King's Birthday.

  • August · good

    In its favour: share of daylight that is sunny 80%, precipitation 81 mm / 3.2 in, days with heavy rain 1.4 days, average daily high 28.9 °C / 84 °F.

    Against: feels like (high) 33.7 °C / 93 °F, wet days 17.2 days, relative humidity 79%, average daily low 27.1 °C / 81 °F.

Beach and swimming

Hot, dry and sunny. Penalises the monsoon hard.

  1. JJanuary: best
  2. FFebruary: best
  3. MMarch: best
  4. AApril: good
  5. MMay: good
  6. JJune: good
  7. JJuly: best
  8. AAugust: best
  9. SSeptember: good
  10. OOctober: neither
  11. NNovember: neither
  12. DDecember: good
Best
January–March, July–August
Good
April–June, September, December

Ko Samui's sea stays warm and inviting all year, and January-March plus July-August are best with light rain; April-June run hotter than the beach-ideal range, and the monsoon peak in October-November brings too much heavy rain to be a good beach month.

Why these months

  • January · best

    In its favour: average daily high 27.2 °C / 81 °F, share of daylight that is sunny 89%, feels like (high) 30.8 °C / 87 °F, precipitation 85 mm / 3.4 in, days with heavy rain 2 days, average daily low 26 °C / 79 °F, wind (daily max) 22 km/h / 14 mph.

    Against: wet days 9.7 days.

    Also on: Buffalo Fighting Festival.

    Watch out for: Chinese New Year travel rush, Christmas and New Year's travel rush.

  • February · best

    In its favour: average daily high 27.5 °C / 82 °F, precipitation 44 mm / 1.7 in, share of daylight that is sunny 91%, feels like (high) 31.6 °C / 89 °F, days with heavy rain 1.1 days, wet days 6.7 days, average daily low 26.4 °C / 80 °F, wind (daily max) 22 km/h / 14 mph.

    Also on: Makha Bucha.

    Watch out for: Chinese New Year travel rush.

  • March · best

    In its favour: average daily high 28.2 °C / 83 °F, share of daylight that is sunny 90%, feels like (high) 33.5 °C / 92 °F, precipitation 84 mm / 3.3 in, days with heavy rain 1.7 days, wet days 8.4 days, wind (daily max) 21 km/h / 13 mph, average daily low 27 °C / 81 °F.

    Also on: Ko Samui Midnight Run, Makha Bucha, Whale shark encounters at Sail Rock.

  • April · good

    In its favour: average daily high 29.1 °C / 84 °F, share of daylight that is sunny 89%, wind (daily max) 19 km/h / 12 mph, average daily low 27.6 °C / 82 °F.

    Against: precipitation 118 mm / 4.7 in, days with heavy rain 3 days, feels like (high) 35.3 °C / 96 °F, wet days 12.4 days.

    Also on: Buffalo Fighting Festival, Songkran, Whale shark encounters at Sail Rock.

  • May · good

    In its favour: average daily high 29.5 °C / 85 °F, share of daylight that is sunny 83%, wind (daily max) 20 km/h / 12 mph, average daily low 27.6 °C / 82 °F.

    Against: precipitation 127 mm / 5 in, wet days 21.1 days, days with heavy rain 3.3 days, feels like (high) 35.4 °C / 96 °F.

    Also on: Whale shark encounters at Sail Rock.

  • June · good

    In its favour: average daily high 29.5 °C / 85 °F, share of daylight that is sunny 80%, precipitation 79 mm / 3.1 in, days with heavy rain 1.4 days, wind (daily max) 23 km/h / 14 mph, average daily low 27.5 °C / 82 °F.

    Against: wet days 17.1 days, feels like (high) 34.5 °C / 94 °F.

  • July · best

    In its favour: average daily high 29.1 °C / 84 °F, share of daylight that is sunny 75%, feels like (high) 33.7 °C / 93 °F, precipitation 86 mm / 3.4 in, days with heavy rain 2 days, wind (daily max) 23 km/h / 15 mph, average daily low 27.2 °C / 81 °F.

    Against: wet days 18.1 days.

    Also on: King's Birthday.

  • August · best

    In its favour: average daily high 28.9 °C / 84 °F, share of daylight that is sunny 80%, feels like (high) 33.7 °C / 93 °F, precipitation 81 mm / 3.2 in, days with heavy rain 1.4 days, wind (daily max) 23 km/h / 14 mph, average daily low 27.1 °C / 81 °F.

    Against: wet days 17.2 days.

  • September · good

    In its favour: average daily high 28.5 °C / 83 °F, share of daylight that is sunny 73%, feels like (high) 33 °C / 91 °F, wind (daily max) 23 km/h / 14 mph, average daily low 26.8 °C / 80 °F.

    Against: precipitation 142 mm / 5.6 in, wet days 22.2 days, days with heavy rain 4.1 days.

  • December · good

    In its favour: average daily high 27.5 °C / 82 °F, share of daylight that is sunny 85%, feels like (high) 30.9 °C / 88 °F, average daily low 26.2 °C / 79 °F, wind (daily max) 23 km/h / 14 mph.

    Against: precipitation 160 mm / 6.3 in, days with heavy rain 4.7 days, wet days 13.6 days.

    Watch out for: Christmas and New Year's travel rush.

An activity is listed only where it applies: skiing at ski destinations, beach and swimming at beach destinations. The nearest ski area is Jade Dragon Mountain, 1954 km away.

Weather averages

Monthly averages over twenty years, 2006–2025. Highs, lows and precipitation are in the chart at the top.

  JanFebMarAprMayJunJulAugSepOctNovDec
Feels like (high) 30.8 °C31.6 °C33.5 °C35.3 °C35.4 °C34.5 °C33.7 °C33.7 °C33 °C32.7 °C32 °C30.9 °C
Days with heavy rain 2 days1.1 days1.7 days3 days3.3 days1.4 days2 days1.4 days4.1 days8.8 days9.9 days4.7 days
Time rain usually falls 8 am2 pm12 pm10 am7 pm6 pm5 pm6 pm5 pm6 am7 am1 am
Sunshine per day 10.4 h10.8 h10.9 h11 h10.5 h10.1 h9.5 h9.9 h8.8 h8.9 h8.8 h9.8 h
Relative humidity 78%78%79%79%80%78%79%79%80%82%82%79%

Sea temperature

Averaged over a shorter period (2022–2025) than the twenty-year averages above.

  JanFebMarAprMayJunJulAugSepOctNovDec
Sea temperature 2022–202528.4 °C29.1 °C29.8 °C31.5 °C31.9 °C30.9 °C30.6 °C30.7 °C30.1 °C30.3 °C29.5 °C28.5 °C
Sea temperature (daily max) 2022–202528.6 °C29.3 °C30 °C31.7 °C32.1 °C31 °C30.7 °C30.9 °C30.3 °C30.5 °C29.7 °C28.7 °C
  • Very cold 10 °C or less
  • Cold 10 to 15 °C
  • Cool 15 to 20 °C
  • Comfortable 20 to 25 °C
  • Warm 25 to 28 °C
  • Very warm over 28 °C

The words describe how the water feels to swim in. They are ours, not an official standard.

Air quality

Averaged over a shorter period (2022–2025) than the twenty-year averages above, and not counted towards good or best months.

  JanFebMarAprMayJunJulAugSepOctNovDec
Air pollution (PM2.5) 2022–202515.4 µg/m³14.1 µg/m³14.7 µg/m³11 µg/m³7 µg/m³7 µg/m³7.7 µg/m³5.6 µg/m³5.1 µg/m³5.7 µg/m³8.7 µg/m³10.4 µg/m³
Air pollution (PM2.5, daily peak) 2022–202520.1 µg/m³18 µg/m³18.8 µg/m³14.7 µg/m³9.7 µg/m³9.2 µg/m³10.3 µg/m³7.7 µg/m³6.9 µg/m³8.9 µg/m³11.9 µg/m³14.5 µg/m³
  • Good 15 µg/m³ or less
  • Fair 15 to 25 µg/m³
  • Moderate 25 to 37.5 µg/m³
  • Poor 37.5 to 50 µg/m³
  • Very poor 50 to 75 µg/m³
  • Extremely poor over 75 µg/m³

Each figure is compared with the World Health Organization's guideline for a day's air, 15 µg/m³ or less, and with its interim targets above that. The words are ours: the WHO does not name its steps. The figures are modelled monthly averages, so single days can be well above them. The daily peak is the average of each day's highest hour, shaded on the same scale.

Events and seasons

What the weather records cannot show. A major event can lift a month to good or best. The warnings are there to help you plan, and never count against a month.

Reasons to go

  • Buffalo Fighting Festival

    January and April

  • Makha Bucha

    February and March, dates vary from year to year

  • Ko Samui Midnight Run

    March

  • Whale shark encounters at Sail Rock

    March, April and May

  • Songkran

    13–15 April

  • King's Birthday

    28 July

  • Loy Krathong

    November, dates vary from year to year

Worth knowing before you go

  • Christmas and New Year's travel rush

    January and December

  • Chinese New Year travel rush

    January and February, dates vary from year to year

Other places in Thailand

Compare places month by month on the travel calendar

Monthly averages over 2006–2025, unless stated otherwise.

Weather data by Open-Meteo.com (CC-BY 4.0), generated using Copernicus Climate Change Service information (ERA5). City data from GeoNames (CC-BY 4.0). Air quality from the Copernicus Atmosphere Monitoring Service (CAMS) and sea temperature from Météo-France / Copernicus Marine, both via Open-Meteo.com. Coastline from Natural Earth. Ski areas from OpenSkiMap.org, © OpenStreetMap contributors (ODbL) and Skimap.org. World Heritage sites from Wikidata (CC0), from the World Heritage List © UNESCO World Heritage Centre. Readership from Wikimedia pageview data (CC0). Destination classification derived from English Wikivoyage, © Wikivoyage contributors (CC BY-SA 4.0).