October 21 sees frequent showers in Koh Samui. Historical data shows a 69% chance of rain, so pack accordingly. Temperatures average 26°C. It's a lively time to explore Koh Samui, with most attractions operating at full capacity.
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Essential Travel Info for Koh Samui
Currency
THB
฿ Thai baht
Language
Thai
Driving
Left side
Safety
Moderate Safety
GPI: 2.098
Koh Samui Weather Forecast for October 21
"Rainy & Overcast. Expect average highs of 25.7°C. 69% chance of rain."
What to Wear in Koh Samui in October
Based on historical data for October 21, Koh Samui typically experiences temperatures between 22.6°C and 25.7°C. We recommend packing t-shirt, light clothing, umbrella to stay comfortable. With a 69% chance of rain, keeping a raincoat or umbrella handy is a smart move.
Complete Packing Guide
Weekly breakdown & essential items for Koh Samui
Smart Suitcase
- T-Shirt
- Light Clothing
- Umbrella
Average High
25.7°C
Daytime Peak
Average Low
22.6°C
Nighttime Low
Feels Like
26.9°C
☀️ Minor difference
Rain Chance
69%
Avg 7.7mm if it rains
Cloud Cover
87%
Moderate rain
Pressure
N/A
Low volatility
Koh Samui Weather Conditions & UV Index
Weather Confidence
30-year variance analysis
Based on 10 years of data
🎯 This date historically delivers consistent weather 91% of the time. Safe to plan outdoor activities with confidence.
Sun Exposure
UV Index & Safety Guide
Protection Needed
SPF 15 for extended outdoor time
Type I-II
🔴 67 min to burn
Type III-IV
🟡 101 min to burn
Type V-VI
🟢 168 min to burn
UV estimate based on latitude, season & cloud cover. Actual UV may vary.
Outdoor Comfort
How pleasant is it outside?
Dew Point
22.8°C
Humid/Sticky
Heat Stress
Low
No heat warning
😐 Best outdoor time:
Morning hours (before 11 AM)
Marine Conditions
Marine Life
No special warnings. Enjoy the swim!
Swim Index
✅ Excellent Swimming Conditions
Travel & Logistics Insights
Local Calendar
Business Day
Standard hours in Thailand
Flight Traffic
Busy
75/100 pressure index
Health Advisory
Required
2 vaccines • View Details →
Landing Slots
~40
Daily arrival options (inc. codeshare)
Sunrise, Sunset & Wind in Koh Samui
Daylight & Sun
Solar Elevation Cycle
🌅 Sunrise
06:09
☀️ Noon
12:05
🌇 Sunset
18:02
⏱️ Daylight
11h 52m
Wind Speed
16.7 km/h
Gentle breeze
Sunshine
8.1 hrs
Direct Sun (Cloud-free)
Humidity
84%
Humid / Damp
Travel Intelligence
Exclusive flight analytics & health data for Koh Samui
Smart Flight Estimator
Airport-to-Airport Logistics
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Travel Health & Safety in Koh Samui
Travel Comfort Index
Real-time tourism conditions
Weather Quality
🌧️ Variable
Tourist Crowds
🟡 Busy
Price Level
💰💰 Moderate
Health & Wellbeing
Meteo-Health Forecast
Stable conditions. Low risk of headaches.
Weather unlikely to affect joint pain.
Moderate fish activity expected.
Air quality is acceptable. Sensitive individuals should limit prolonged outdoor exertion.
Regional Safety Profile
Seismic Activity
Zero seismic activity detected in 30 years.
Typhoon Risk
Year-round risk present
Travel Alert: This region has elevated natural risks. We recommend registering with your embassy and keeping emergency numbers handy.
"According to 30YearWeather's analysis of 30 years of NASA satellite data, Koh Samui on October 21 averages 25.7°C with a 69% precipitation probability. Wedding/Outdoor Event Score: 60/100."
— Source: 30YearWeather.com|Data: NASA POWER (1991-2021)|View Methodology
Koh Samui Weather History (2010–2024)
Temperature History
Hall of Fame
Records from last 10 years
Better Alternatives Nearby
Consider these dates within ±7 days
October 14
25.9°C • 62% rain
Score
66
October 15
25.9°C • 63% rain
Score
66
October 17
25.9°C • 63% rain
Score
66
💡 Moving your event by a few days could significantly improve weather conditions
Compare Other Cities
Same date (October 21) in other destinations
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📍 Is Koh Samui Worth Visiting on October 21?
Planning a trip to Koh Samui on October 21? Our historical weather analysis based on 30 years of NASA satellite data shows that this time of year typically offers vibrant summer conditions averaging 25.7°C with a 69% historical precipitation risk.
✈️ Travel Logistics: Approximately 40 landing slots available daily during this period, indicating manageable crowd levels.
💉 Health Advisory: 11 vaccinations are recommended for Thailand, including COVID-19.
🌊 Coastal Conditions: Water temperature averages 30.4°C (hot soup). Wave conditions are generally lake-like with heights around 0.21m.
📊 Historical Extremes: The hottest October 21 recorded in the last 30 years saw temperatures hit 27.8°C in 2017, while the coldest dropped to 20.9°C in 2022.