Ko Lanta weather in September

In September, Ko Lanta sees average daytime highs of 28°C and overnight lows near 26°C, with 302 mm of rain across 24.4 wet days and about 12 hours of daylight. It is the 10th-warmest and 2nd-wettest month of the year here.

Day-to-day highs hold fairly steady near 28°C through the month. The sky is clear or mostly clear about 3% of the time in September, and the air most often feels oppressive.

Daylight stretches from about 12 h 06 min at the start of September to 11 h 54 min by month's end. Set against the rest of the year, September is Ko Lanta's 11th-clearest and 4th-windiest month. For the whole year in context, see Ko Lanta's year-round climate.

Daytime high
28°
10th warmest
Overnight low
26°
6th coldest
Rainfall
302 mm
24.4 wet days
Daylight
12 hours
6:17 AM – 6:19 PM
Cloud cover
85%
11th clearest
Wind
17 km/h
4th windiest
Solar energy
5.1 kWh/m²
Travel score
3.8
out of 10

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 28°C through the month.

A typical September day in Ko Lanta reaches about 28°C in the afternoon and slips back to 26°C overnight — a 2°C spread between the day's warmth and the night's chill. On most days the high lands between 27°C and 29°C. Set against its neighbours, September runs on par with August and on par with October.

24°26°28°30°32°151015202530
Avg high (°C)Avg low (°C)
12826
22826
32826
42826
52826
62826
72826
82826
92826
102826
112826
122826
132826
142826
152826
162826
172826
182826
192826
202826
212826
222826
232826
242826
252826
262826
272826
282826
292826
302826

How September really feels in Ko Lanta

Once humidity and wind are folded in, September averages 5 days that feel above 32°C and 0 that feel at or below 0°C — the comfort signal a plain temperature reading hides.

Days feeling ≥ 32°C
5
heat index over the day's high
Days feeling ≤ C
0
wind chill below the day's low

The story in September is heat — humidity pushes the afternoon "feels like" well above the raw temperature.

Ko Lanta weather by month

How September compares with the rest of the year at a glance. September is the 10th-warmest and 2nd-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan28° / 26°466.311.66.2
Feb29° / 26°25411.86.3
Mar29° / 27°8310.911.95.4
Apr29° / 27°14819.912.24.1
May29° / 27°25825.212.33.5
Jun29° / 27°22921.912.43.8
Jul29° / 27°22722.112.43.9
Aug28° / 27°27022.612.24.0
Sep28° / 26°30224.4123.8
Oct28° / 26°32728.311.83.6
Nov28° / 26°2232311.74.2
Dec28° / 26°10512.311.65.4

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 3% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 7% of September, with mostly cloudy or overcast conditions the remaining 90%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
11189
21189
31189
41189
51189
61189
71189
81189
91189
10991
111090
121090
131090
141090
151189
161189
171189
181189
191189
201288
211090
221090
231090
241090
251090
26991
27991
28892
29793
30793

Chance of precipitation in September

Any precipitation

Ko Lanta gets around 302 mm of rain over 24.4 wet days in September. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 82% and peaks near 88% on the wettest days. The odds climb toward the end of the month.

0%20%40%60%80%100%151015202530
Rain chance (%)
179
279
379
480
580
680
780
880
980
1081
1181
1281
1381
1481
1581
1681
1781
1881
1981
2081
2182
2282
2383
2483
2584
2685
2786
2886
2987
3088

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

Most of September feels oppressive — the stacked bands show each day's mix of comfort levels, read off the dew point.

By dew point, September lands in the oppressive band about 57% of days. Sticky, muggy-or-worse air turns up on roughly 100% of them.

0%25%50%75%100%151015202530
Oppressive (%)Miserable (%)
15446
25446
35545
45644
55644
65644
75644
85644
95644
105545
115545
125545
135446
145446
155446
165446
175446
185545
195545
205545
215644
225743
235743
245842
255941
266040
276139
286238
296337
306436

Wind in September

Winds average 17 km/h in September.

Across September, daily wind ranges from about 17 km/h on the calmest days to 18 km/h at its breeziest. It stays fairly steady from day to day.

05101520151015202530
Wind speed (km/h)Feels
117light breeze
217light breeze
317light breeze
417light breeze
517light breeze
617light breeze
717light breeze
817light breeze
917light breeze
1017light breeze
1117light breeze
1218light breeze
1318light breeze
1418light breeze
1518light breeze
1618light breeze
1718light breeze
1818light breeze
1918light breeze
2018light breeze
2117light breeze
2217light breeze
2317light breeze
2417light breeze
2517light breeze
2617light breeze
2717light breeze
2817light breeze
2917light breeze
3017light breeze

Sunrise & sunset in September

DaylightNight

Daylight runs from about 12 h 06 min at the start of September to 11 h 54 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 12 minutes over September. Sunrise moves from 6:19 AM to 6:15 AM, and sunset from 6:28 PM to 6:11 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.16:196:28
212.16:196:27
312.16:196:27
412.16:196:26
512.16:186:26
612.16:186:25
712.16:186:24
812.16:186:24
912.16:186:23
1012.16:186:23
1112.16:186:22
1212.16:176:22
1312.16:176:21
1412.16:176:20
1512.06:176:20
1612.06:176:19
1712.06:176:19
1812.06:166:18
1912.06:166:17
2012.06:166:17
2112.06:166:16
2212.06:166:16
2312.06:166:15
2412.06:166:15
2512.06:156:14
2612.06:156:13
2712.06:156:13
2812.06:156:12
2911.96:156:12
3011.96:156:11

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 5.1 kWh/m².

For context, solar energy here swings from a low near 4.66 kWh/m² to a high of 6.42 kWh/m² in March across the year — September's 5.1 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
15.2Bright
25.2Bright
35.2Bright
45.2Bright
55.2Bright
65.2Bright
75.2Bright
85.1Bright
95.1Bright
105.1Bright
115.1Bright
125.1Bright
135.1Bright
145.1Bright
155.1Bright
165.0Bright
175.0Bright
185.0Bright
195.0Bright
205.0Bright
215.0Bright
225.0Bright
235.0Bright
245.0Bright
255.0Bright
264.9Bright
274.9Bright
284.9Bright
294.9Bright
304.8Bright
Planning a trip in September

Hazard calendar for Ko Lanta

In seasonPeak

In September, Ko Lanta sits inside its cyclone and rainy season season. The full year is below, with each hazard's peak months called out.

Ko Lanta sits in the North Indian Ocean cyclone zone; the season peaks May and October–November.

Ko Lanta's rainy season runs April–November, when most of the year's rain falls.

Cyclone
Rainy season
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

Is September a good time to visit Ko Lanta?

Our two travel scores rate September for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).

3.8
Sightseeing
9th-best month of the year
4.2
Beach & pool
11th-best month of the year

September is a weaker month for outdoor sightseeing in Ko Lanta.

What to pack for Ko Lanta in September

From September's temperature range, rain chance, sun and wind — what's worth putting in the bag.

In September, Ko Lanta sees daytime highs around 28°C and nights near 26°C. Pack light clothes and rain gear. Worth having: sun protection. About 24 days see rain.

light clothesrain gearsun protection

Sea temperature near Ko Lanta in September

The nearest coast averages about 29°C in September — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea offshore is warmest in May at about 30°C and coldest in January near 29°C.

The water stays above 20°C all year — warm enough for a swim any month.

28°30°32°JanFebMarAprMayJunJulAugSepOctNovDecwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan29Tropical
Feb29Tropical
Mar30Tropical
Apr30Tropical
May30Tropical
Jun30Tropical
Jul30Tropical
Aug30Tropical
Sep29Tropical
Oct29Tropical
Nov29Tropical
Dec29Tropical

UV index in Ko Lanta in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 13 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Ko Lanta peaks around February 22 at about 13 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near November 22 at about 10 (extreme).

The index reaches 3 or more — the level where the WHO recommends sun protection — every month of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecExtremeFeb 22UV 13Nov 22UV 10
UV index (midday)Level
Jan11Extreme
Feb13Extreme
Mar13Extreme
Apr13Extreme
May12Extreme
Jun12Extreme
Jul11Extreme
Aug13Extreme
Sep13Extreme
Oct12Extreme
Nov10Extreme
Dec10Extreme

Air quality in Ko Lanta in September

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where September falls, not just the annual average.

Air quality in Ko Lanta is worst in April — around 16 µg/m³ PM2.5 (moderate), and holds fairly steady the rest of the year.

Modeled monthly averages (CAMS reanalysis, 2015–2024).

01020JanFebMarAprMayJunJulAugSepOctNovDecModerateGoodGoodModerateApr 1115 µg/m³Aug 2011 µg/m³
PM2.5 (µg/m³)Level
Jan15Moderate
Feb14Moderate
Mar15Moderate
Apr16Moderate
May13Moderate
Jun13Moderate
Jul13Moderate
Aug11Good
Sep12Moderate
Oct12Good
Nov12Good
Dec13Moderate
Location & terrain

Where is Ko Lanta?

Ko Lanta sits at 7.5°N, 99.1°E, 0 m above sea level, in Thailand. The nearest listed city is Ko Phi Phi, 42 km away.

Topography around Ko Lanta

How much the land rises and falls, and what covers it, within 3, 16 and 80 km of Ko Lanta.

Within 3 km, the terrain around Ko Lanta has significant variations in elevation — a maximum elevation change of 481 m around an average of 77 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 487 m; within 80 km, large variations in elevation — a maximum elevation change of 1,003 m.

The land around Ko Lanta is covered by trees (53%) and water (41%) within 3 km, water (82%) within 16 km, and water (59%) and trees (36%) within 80 km.

3 km
481 m
16 km
487 m
80 km
1,003 m
treesgrasslandartificial surfaceswatermangroves
September weather nearby: Ko Phi Phi 42 km · Trang 58 km · Krabi 63 km · Ao Nang 65 km · Huai Yot 67 km · Ban Ko Sire 83 km · Ban Talat Yai 85 km · Phuket 86 km

Thailand travel facts

Travel advisory
Level 1
Exercise Normal Precautions
Power plugs
Type A / B / C
230 V · 50 Hz
Prices
≈ 31% of US
price level, 2025
GDP per capita
$8,057
2025
Happiness
6.3 / 10
World Happiness, 2025
Homicide rate
4.8
per 100k, 2011
Road deaths
32.2
per 100k/yr, 2019
Income group
Upper middle
World Bank
English
Very low
EF EPI 402
Religion
Buddhist 93%Muslim 5%Christian 1%other 1%

Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.

Data sources

Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Ko Lanta (7.5336°, 99.0865°, elevation 0 m), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google. Tropical-cyclone seasons are the published climatological basin seasons (NOAA National Hurricane Center / regional warning centres). Sea temperatures are the NOAA OISST v2.1 1991–2020 monthly climatology (public domain), sampled at the nearest ocean point. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Monthly air-quality (PM2.5) seasonality is from the CAMS EAC4 reanalysis (Copernicus Atmosphere Monitoring Service), scaled to the WHO annual mean where available. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).