For a Koh Samui vacation of beach walks and relaxed days at your accommodation, consider February–April. Unlike Phuket and Krabi, Samui gets heavy rain from October through December, with November averaging 444.6 mm, so the same dry-season calendar does not work for both coasts. February is driest at 64.3 mm, with an average temperature of 27.4°C. It gets hotter toward April; plan beach walks in the morning and evening, with time to rest indoors at midday.
The figures below are 1991–2020 climate normals. The observing station is KO SAMUI; actual conditions at beaches, mountains or your accommodation can differ. Scroll the table sideways.
| Month | Average temperature | Average high | Average low | Rainfall | Rainy days |
|---|---|---|---|---|---|
| January | 26.9°C | 29.0°C | 24.2°C | 126.8mm | 11.1 days |
| February | 27.4°C | 29.4°C | 24.9°C | 64.3mm | 5.6 days |
| March | 28.2°C | 30.4°C | 25.4°C | 115.8mm | 5.9 days |
| April | 29.1°C | 31.8°C | 26.0°C | 82.9mm | 8.1 days |
| May | 29.2°C | 32.9°C | 25.7°C | 131.6mm | 14.0 days |
| June | 28.8°C | 32.7°C | 25.3°C | 133.6mm | 13.1 days |
| July | 28.5°C | 32.3°C | 25.1°C | 117.0mm | 14.3 days |
| August | 28.4°C | 32.4°C | 25.1°C | 102.2mm | 14.5 days |
| September | 28.0°C | 31.9°C | 24.8°C | 117.5mm | 15.0 days |
| October | 27.4°C | 30.6°C | 24.3°C | 294.9mm | 19.3 days |
| November | 27.1°C | 29.7°C | 24.1°C | 444.6mm | 18.7 days |
| December | 26.8°C | 29.3°C | 24.0°C | 263.1mm | 14.2 days |
The station table is on PDF page 77. Rainy-day numbers are averages and do not mean all-day rain.
Benefits and cautions are itinerary suggestions based on climate data. Read the actual day’s weather and marine activity operating decisions separately before leaving.
What works well this month
Plan time both to rest at your accommodation and to explore a nearby beach. Wait indoors during rain, then head out again when it eases.
What to keep in mind
During the seasonal transition, do not count on clear skies every day. Read the forecast before booking outdoor activities.
What works well this month
Walk by the sea in the morning and relax at your accommodation during the day. This suits a trip combining beach walks with plenty of rest.
What to keep in mind
Even with little rain, midday can be hot and showers remain possible. Pack a hat and a lightweight umbrella.
What works well this month
Walk along the shore in the morning or late afternoon, then eat or relax at your accommodation during the day.
What to keep in mind
Even with little rain, midday can be hot and showers remain possible. Pack a hat and a lightweight umbrella.
What works well this month
Walk on the beach in the morning or evening and rest at your accommodation during the hot part of the day. Breaks between meals and outings keep you from spending long hours outside at midday.
What to keep in mind
Long walks at midday can be tiring. Carry water and rest in the shade between outings.
What works well this month
Enjoy beach walks during the cooler hours. Eat indoors or rest at your accommodation during the day, then head out again as the sun drops.
What to keep in mind
Long walks at midday can be tiring. Carry water and rest in the shade between outings.
What works well this month
Visit the beach in the morning and rest at your accommodation during the day. You can enjoy sea views while avoiding the midday heat.
What to keep in mind
Even with little rain, midday can be hot and showers remain possible. Pack a hat and a lightweight umbrella.
What works well this month
Divide your plans between beach walks and rest at your accommodation. Eat indoors during the hot hours and head out again later in the afternoon.
What to keep in mind
Even with little rain, midday can be hot and showers remain possible. Pack a hat and a lightweight umbrella.
What works well this month
Enjoy a vacation relaxing at your accommodation and looking out to sea. If you want a walk, go in the morning or evening rather than the hot midday hours.
What to keep in mind
Even with little rain, midday can be hot and showers remain possible. Pack a hat and a lightweight umbrella.
What works well this month
After a morning beach walk, rest at your accommodation. Return to the shore in the evening to enjoy your trip outside the midday heat.
What to keep in mind
Even with little rain, midday can be hot and showers remain possible. Pack a hat and a lightweight umbrella.
What works well this month
During heavy rain, relax at your accommodation or eat indoors. Take a short walk nearby once the rain eases.
What to keep in mind
Check waves and wind as well as rainfall. Adjust your plans to boat operating decisions and beach swimming restrictions.
What works well this month
Leave plenty of time to rest at your accommodation and enjoy meals nearby. Choose outdoor sightseeing times according to the day’s rain forecast.
What to keep in mind
Check waves and wind as well as rainfall. Adjust your plans to boat operating decisions and beach swimming restrictions.
What works well this month
Take your time over indoor meals and rest at your accommodation. When the rain eases, enjoy a short walk nearby.
What to keep in mind
Check waves and wind as well as rainfall. Adjust your plans to boat operating decisions and beach swimming restrictions.
Plan Beach walks in the morning or around sunset. Set aside midday for meals and rest to avoid long walks in the heat. On rainy days, consider Relaxing at your accommodation between meals and short outings.
Before entering the sea, follow beach flags and local swimming restrictions. Read the operator’s same-day instructions for boat transfers and island tours, and check cancellation and change terms before booking.
February–April suits a beach vacation. Samui’s wetter end of the year means Phuket’s recommended dates cannot simply be carried over. February has the lowest rainfall, while April’s average rises to 29.1°C. Consider how comfortably you handle heat as well as rain when choosing your dates.
Look at average highs and lows too. The average temperature is not a reading at one particular time of day. Prepare separately for midday walks and for mornings or evenings outside.
No. Rainy-day counts are monthly averages, not the hours or duration of rainfall. Read the hourly forecast for your actual travel dates and adjust outdoor plans.
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