Temperature
Hot by day, warm at night.
90°Ftypical September high
Typical range
September climate
September in Ko Samui
Thailand · Southeast Asia
Hot days. Typhoon risk near peak and humid air are the main drawbacks.
Some tradeoffs
Daytime high
90°F
Lows around 78°F
Rain
Rain most days
Sun
5 h/day
Air feel
Very humid
Sea temp
85°F
Great for swimming
When to visit
Month-by-month fit
Best
Precipitation
It rains on most days. About 23 wet days, more than in most months.
77%wet-day frequency
AmountWet-day chance
Sunshine
Sunshine is limited, with cloud often dominating.
4.8 hSeptember sunshine
Heat & humidity by month
Very hot days with very humid air.
100%September Heat feel
Easy airWarm airHumid air
Hourly temperature pattern
In September, afternoons feel about 87° and nights feel near 84°.
WarmHotNight hours
Clear sky
Overcast skies this month.
13%September Clear sky
Clear skyCloud
Wind pattern
September's typical breeze keeps the air from feeling as stagnant.
11 mphSeptember Breezy
Sea temperature
85°FSeptember sea temp
More detailIncludes daypart comfort
Typical September day
September stays around 82°F through the day and night, with little temperature relief.
Avg temp Typical range
Morning81°F
Feels 85°F
Rain32%
Cloud87%
Humid airVery high
Sun intensityModerate
Midday82°F
Feels 86°F
Rain28%
Cloud84%
Humid airVery high
Sun intensityStrong
Late afternoon82°F
Feels 86°F
Rain37%
Cloud81%
Humid airVery high
Sun intensityModerate
Early evening82°F
Feels 86°F
Rain43%
Cloud87%
Humid airVery high
Sun intensityMinimal
Best windowData tableView month-by-month numbers
View month-by-month numbers
| Month | High°F | Low°F | Rainin | Wet days | Sunh | Humidity% | Sea°F |
|---|---|---|---|---|---|---|---|
| Jan | 85 | 77 | 5.0 | 10 | 6.4 | 78 | 83 |
| Feb | 85 | 78 | 2.5 | 5 | 7.6 | 78 | 83 |
| Mar | 87 | 79 | 4.6 | 9 | 7.7 | 79 | 85 |
| Apr | 90 | 80 | 3.3 | 11 | 6.7 | 79 | 86 |
| May | 93 | 80 | 5.2 | 21 | 6.2 | 79 | 87 |
| Jun | 93 | 79 | 5.3 | 21 | 5.0 | 78 | 86 |
| Jul | 92 | 78 | 4.6 | 21 | 5.0 | 79 | 85 |
| Aug | 92 | 78 | 4.0 | 18 | 4.9 | 79 | 85 |
| Sep | 90 | 78 | 4.6 | 23 | 4.8 | 81 | 85 |
| Oct | 89 | 77 | 11.6 | 28 | 4.7 | 82 | 85 |
| Nov | 86 | 76 | 17.5 | 21 | 5.8 | 82 | 84 |
| Dec | 85 | 76 | 10.4 | 14 | 5.7 | 78 | 83 |
Similar climates
Similar
Similar travel styleNosaraCosta RicaSimilar travel styleSanta TeresaCosta RicaSimilar travel styleNegrilJamaicaSimilar travel styleBaliIndonesia
Want a side-by-side climate view? Compare Ko Samui with Nosara.
Climate data notePlanning guidance, not a forecast
Typical monthly values are based on long-term climate records. Useful for planning, not a forecast. Check the weather before you travel.
Sunshine: source type is not yet identified at metric level.
Local microclimates can vary by beach, neighborhood, trail, or elevation.
Last updated: Jun 28, 2026
Data & methodology