If you’re planning a winter trip to Koh Samui, get ready for warm tropical weather that barely shifts from day to night. Average daytime temperatures hover around 29°C (84–86°F), and nights drop only a bit, settling at about 25–26°C (77–79°F).
That means you can spend your days on the beach, exploring, or eating outside without battling the scorching heat that comes later in the year.
Rainfall changes fast during winter. December tends to hang onto monsoon showers, but by January and February, the skies brighten up, and sunshine sticks around. You’ll notice rain comes in short bursts instead of long storms, and dry, sunny days get more common as winter goes on.
The sea keeps warm, around 27–28°C (81–82°F), so you can swim, snorkel, or hop on a boat without worrying about chilly water.
After December, the winds calm down, making ferry rides and water sports smoother. This combo of steady warmth, lighter rain, and inviting sea really makes winter a solid time to visit Koh Samui.
Overview of Koh Samui’s Winter Climate
Winter months in Koh Samui stay warm and humid, and temperatures barely budge. Rain falls less often than in the wetter months.
Daylight hours don’t change much, so you get consistent conditions for outdoor fun.
Typical Winter Temperatures
Koh Samui’s tropical climate means you won’t run into cold weather here. Daytime highs usually hit 85°F to 87°F (29°C to 31°C), while nighttime lows hover around 78°F (25°C).
There’s not much difference between day and night, so you’ll always feel warm.
January and February do cool off a touch compared to March, but honestly, it’s barely noticeable. The heat stays pretty moderate compared to the blazing summer, which draws plenty of travelers this time of year.
Here’s a quick look at average winter temperatures:
| Month | High °F (°C) | Low °F (°C) |
|---|---|---|
| December | 85 (29) | 78 (25) |
| January | 85 (29) | 78 (25) |
| February | 87 (31) | 79 (26) |
The sea stays toasty too, around 82°F to 84°F (28°C to 29°C), so swimming and diving feel great.
Humidity and Comfort Levels
Koh Samui keeps humidity high year-round, and winter doesn’t really break that trend. The air often feels muggy or oppressive, with humidity levels close to 80–90%.
Since the island sits in a tropical zone, the dew point stays high, so your skin might not cool off easily.
Even with the humidity, winter feels more comfortable than the monsoon season. You’ll see fewer heavy downpours and more sunshine, which helps balance out the dampness.
If you’re sensitive to heat, try to plan your outings in the morning or evening when it’s a bit cooler. Light clothes, shade, and staying hydrated make a big difference here.
Length of the Winter Season
Winter in Koh Samui isn’t about cold weather, but about drier, clearer skies. This season usually runs from mid-December through early March.
Rain drops off compared to the long wet season, and skies often stay clear.
Daylight hours stay steady, about 11.5 to 12.5 hours a day. Big seasonal shifts just don’t happen here because the island sits so close to the equator.
January and February bring the most stable weather, with less rain and less cloud cover. That’s when you’ll get the best days for the beach, tours, and water sports.
Monthly Breakdown: December, January, and February
These three months bring some of the most comfortable weather you’ll find in Koh Samui. Temperatures stay warm but not overbearing, and rainfall drops off compared to the wettest times of year.
More sunshine means it’s easier to plan your days outside.
December Weather Patterns
December signals the start of the drier season on Koh Samui. Rain falls less than in November, but you might still get scattered showers, especially early in the month.
Average rainfall lands around 150–200 mm, way less than during peak monsoon.
Daytime temperatures usually sit between 26–29°C (79–84°F). Nights cool off a bit, dipping to 24°C (75°F).
Humidity stays moderate, so the air feels lighter than in the wet months.
You’ll get about 6–7 hours of sunshine each day, which makes beach days and boat trips a safer bet.
Tourist areas start to fill up, especially around the holidays. If you’re coming in late December, book ahead—places fill up fast.
January Weather Conditions
January brings some of Koh Samui’s driest, sunniest days. Rain usually drops to less than 100 mm for the month, and many days stay completely dry.
The sea calms down, so ferry rides and snorkeling trips get smoother.
Average daily temperatures range from 25–29°C (77–84°F). Nights are comfy, rarely dipping below 23°C (73°F).
Humidity is lower than in the wet season, so you can spend more time outdoors without feeling sticky.
There’s also 7–8 hours of sunshine a day, some of the best all year. January’s a smart pick if you want steady beach weather.
Resorts and beaches stay lively, and you’ll find reliable conditions for relaxing or getting active on the water.
February Weather Highlights
February keeps the dry season going, with some of the year’s most stable weather. Rain is scarce, often below 50 mm, and skies usually stay clear.
This month is the most predictable for outdoor plans.
Daytime temperatures stay warm, usually 26–30°C (79–86°F), and nights are mild at 24–25°C (75–77°F).
The sea is calm and clear, giving you great visibility for diving and snorkeling.
You’ll get 8–9 hours of sunshine a day, the most during winter. Winds are gentle, so boat trips rarely get canceled.
If you want steady warmth, dryness, and sunshine, February really delivers.
Rainfall and Sunshine During Winter
Winter brings a big shift compared to Koh Samui’s wettest months. Rain drops off steadily, and sunshine becomes more reliable, so you can plan more outdoor activities and beach days.
Rainfall Amounts and Frequency
Rain in winter plunges from the heavy monsoon totals of October and November. December still gets an average of about 210 mm, but that falls off quickly.
By January, you’re looking at about 86 mm, and February is one of the driest months with only 54 mm.
Rainy days follow the same trend. December brings 10–12 wet days, January averages 5–6, and February typically gets just 4–5.
Showers are usually short and scattered, so clear skies return fast.
This drop in rain means you can expect more predictable weather in winter.
While December might still feel humid, January and February bring drier air and fewer interruptions to your plans.
Average Sunshine Hours
Sunshine gets more consistent through winter. December brings 6–7 hours of sun a day, since some monsoon clouds still hang around.
By January and February, skies clear up more, giving you 8–9 hours of sunshine daily.
Daylight doesn’t change much, staying between 11.5 and 12 hours all season.
With less rain, you get longer stretches of daylight for outdoor fun.
The sun packs a punch, with a high UV index often hitting 11–12 at midday. It’s smart to use sun protection, especially if you’re spending hours at the beach.
This combo of steady sunshine and less rain makes winter one of the most comfortable times to enjoy Koh Samui’s coast.
Sea Conditions and Beach Activities
In winter, the sea around Koh Samui stays warm and welcoming. Calm waters and mild weather make it easy to plan swimming and other beach activities.
Sea Temperature in Winter
From December to February, sea temperatures average 28–29°C (82–84°F). That steady warmth means you can stay in the water as long as you want.
Unlike places where winter chills the sea, Thailand’s Gulf keeps a stable, warm climate. Air and water temps are close, so there’s no shock when you dive in.
Daytime sunshine helps too. With about 7–8 hours of sun daily, the water stays pleasant for swimmers and snorkelers.
| Month | Avg. Sea Temp °C | Avg. Sea Temp °F |
|---|---|---|
| December | 28.2 | 82.8 |
| January | 27.8–28.0 | 82.0–82.4 |
| February | 28.1 | 82.6 |
These small changes mean you don’t have to worry about cold water ruining your beach day.
Water Sports and Swimming
Winter makes Koh Samui one of Thailand’s most reliable spots for water activities. The sea is calm and rainfall is low, so snorkeling and diving visibility improves.
You can swim safely at most beaches, since currents are weaker now.
Chaweng and Lamai are favorites for casual swimming, while quieter spots like Bophut offer calm water for families.
Kayaking and paddleboarding are popular too, thanks to flat seas. Jet skiing and parasailing run regularly, though windier days can affect schedules.
If you love snorkeling, coral reefs near Koh Tao and Koh Nang Yuan are easy to reach by boat. Clearer winter seas boost your chances of seeing colorful fish and thriving coral.
Best Time to Visit Koh Samui in Winter
Winter hands Koh Samui its driest, most comfortable stretch—think sunny skies, light breezes, and moderate temperatures. You’ll find ideal conditions for the beach, calm seas, and a lively island vibe, which is why so many people show up this time of year.
Peak Season Overview
From mid-December through February, Koh Samui hits its peak travel season. Daily highs usually run between 25°C and 30°C (77°F–86°F), and humidity drops compared to other times of year.
Rain is rare, so you’ll get long stretches of sunshine.
This is the sweet spot for swimming, snorkeling, and boat trips. Calm seas keep things safe for families, and cooler evenings make outdoor dining a pleasure.
The island gets busy now. Resorts and villas fill up fast, especially around Christmas and New Year, and prices go up. Booking early is a must.
Festivals and events add to the fun. New Year’s brings fireworks and beach parties, and you can catch cultural events for a taste of Thai traditions.
Travel Tips for Winter Visits
Book early if you want the best hotel choices, especially for family trips. Many beachfront resorts have pools and kids’ clubs, but they fill up quickly in winter.
Pack light clothes, sunscreen, and a hat. Even with moderate temps, the tropical sun is intense. A light jacket helps for cooler nights, especially if you’re eating by the water.
Transportation gets busy, so arrange airport transfers and ferry tickets ahead of time. If you want quieter beaches, look at the north or west coasts, where crowds thin out.
For activities, focus on water sports, island tours, and evening markets. Winter brings great visibility for diving and snorkeling, and dry weather opens up hiking trails. This season offers the most reliable conditions for exploring both land and sea.
Impact on Family Holidays and Local Events
In the winter months, Koh Samui keeps things warm and mostly dry. That means families can actually get outside and enjoy the beaches or explore without rain messing up their plans. Local festivals pop up too, so you get a nice mix of holiday and cultural fun.
Winter Activities for Families
Daytime temperatures usually sit between 24°C and 28°C. That’s pretty comfortable, whether you’re traveling with kids or just want to avoid sweating through your shirt.
The sea stays calm and warm, so swimming and snorkeling feel safe for just about everyone.
Most families pick Chaweng or Lamai Beach because they’ve got good facilities. If you’d rather skip the crowds, Maenam Beach is a quieter option.
Lots of resorts provide kids’ clubs. Parents can actually relax while their kids join in on supervised activities.
Outdoor trips, like boat rides out to Ang Thong Marine Park, go smoothly in winter thanks to the calm water. Hiking to waterfalls—Na Muang comes to mind—feels a lot easier when the trails are dry.
If you’re traveling with younger kids, you’ll still find indoor places like aquariums and cultural shows. But honestly, you can count on the weather and plan more outdoor adventures without worrying about last-minute changes.
Festivals and Celebrations
Winter lines up with one of Koh Samui’s busiest cultural stretches. December usually brings a bunch of holiday events at hotels and resorts. You’ll find family-friendly dinners and gatherings right on the beach.
In January and February, you might stumble across local temple fairs. These fairs have food stalls, games, and traditional performances. They welcome families and let you soak up Thai culture without any fuss.
The monthly Full Moon Party over on Koh Phangan isn’t really for families. Still, Koh Samui hosts smaller local celebrations that feel safe and fun for everyone.
Rain barely makes an appearance during this time, so most festivals go ahead as planned. The steady weather means outdoor stages, parades, and cultural shows usually happen without a hitch.