Hottest (avg)
#10 / 12
On the cooler side.
September in context
How it compares to the rest of the year in Bangkok.
Wettest (avg)
#1 / 12
The wettest month of the year.
Daylight Hours
#6 / 12
Around the yearly average.
Windiest (avg)
#11 / 12
Usually calmer than most months.
Highest UV
#5 / 12
Near the middle of the yearly UV range.
Most Humid
#1 / 12
The muggiest month of the year.
Monthly climate breakdown
A detailed look at the typical climate conditions for September.
Thermal profile
Temperature
Typical daytime high
- Nighttime low
-
- Feels like (avg)
-
Light window
Sunshine
12.2 h
Average daylight
- UV index (max)
- 9
- Typical sun hours
- 06:06 - 18:18
Wet-day pattern
Rain & Snow
Typical rainfall
- Rainy days
- 28 days
- Cloud cover (avg)
- 89%
Air feel
Humidity & Wind
83%
Average humidity
- Wind (avg)
-
- Wind (max gusts)
-
Historical daily baseline
Daily climate explorer
Pick a day to inspect the usual conditions through September in Bangkok. Based on a 30-year historical climate baseline, not a forecast.
Primary control
Select a day
Scroll to compare daily conditions. The summary updates with your selection.
Secondary context
Monthly trend
Median daytime highs across the month, with a softer low line.
Median temperatureMedian lowTypical range
Day 15 selected for September. Temperature 30.8°C.
Historical disruption baseline
Typical disruptions in September
Based on 30 years of historical data, these are the disruption patterns most likely to affect plans in September.
Humidity High impact
Muggy days Measures: Muggy days (dew point >=20C). Observed about 100% of days (30.0 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
30.0 days / month
- Share of days
- ~100% of days
- Upper edge
- Up to ~25°C (P95)
Why this matters
Muggy conditions are possible on ~30 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Heat High impact
Hot feels-like days Measures: Hot feels-like days (>=32C). Observed about 99% of days (29.6 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
29.6 days / month
- Share of days
- ~99% of days
- Upper edge
- Up to ~40°C (P95)
Why this matters
Feels-like heat >=32C is possible on ~30 days. Midday activity often needs adjustment around shade, hydration, and indoor fallback options.
Heat High impact
Hot days Measures: Hot days (>=30C). Observed about 78% of days (23.3 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
23.3 days / month
- Share of days
- ~78% of days
- Upper edge
- Up to ~33°C (P95)
Why this matters
Hot days are possible on ~23 days. Midday activity often needs adjustment around shade, hydration, and indoor fallback options.
Heat High impact
Very hot feels-like Measures: Very hot feels-like days (>=35C). Observed about 76% of days (22.9 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
22.9 days / month
- Share of days
- ~76% of days
- Upper edge
- Up to ~40°C (P95)
Why this matters
Very hot feels-like conditions are possible on ~23 days. Midday activity often needs adjustment around shade, hydration, and indoor fallback options.
Heat High impact
Heat stress risk Measures: High heat stress days. Observed about 76% of days (22.9 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
22.9 days / month
- Share of days
- ~76% of days
- Upper edge
- Up to ~40°C (P95)
Why this matters
Heat stress is possible on ~23 days. Midday activity often needs adjustment around shade, hydration, and indoor fallback options.
Rain High impact
Rain disruption Measures: Likely rain disruption days. Observed about 56% of days (16.8 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
16.8 days / month
- Share of days
- ~56% of days
- Upper edge
- Up to ~31mm (P95)
Why this matters
Rain disruption risk appears on ~17 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Show all disruptions (22 more)
Humidity High impact
Oppressive humidity Measures: Oppressive humidity days (dew point >=24C). Observed about 56% of days (16.8 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
16.8 days / month
- Share of days
- ~56% of days
- Upper edge
- Up to ~25°C (P95)
Why this matters
Oppressive humidity is possible on ~17 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Rain High impact
Washout risk Measures: Washout day risk. Observed about 53% of days (15.9 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
15.9 days / month
- Share of days
- ~53% of days
- Upper edge
- Up to ~31mm (P95)
Why this matters
Washout conditions are possible on ~16 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Rain High impact
Heavy rain days Measures: Heavy rain days (>=10mm). Observed about 32% of days (9.5 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
9.5 days / month
- Share of days
- ~32% of days
- Upper edge
- Up to ~40mm (P95)
Why this matters
Heavy rain is possible on ~9 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Rain High impact
Washout run Measures: Multi-day washout runs. Observed about 3.4 days/month in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
3.4 days / month
- Share of days
- —
- Upper edge
- Up to ~33mm (P95)
Why this matters
Multi-day washout runs are possible on ~3 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Rain High impact
Very heavy rain Measures: Very heavy rain days (>=25mm). Observed about 5% of days (1.5 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
1.5 days / month
- Share of days
- ~5% of days
- Upper edge
- Up to ~65mm (P95)
Why this matters
Very heavy rain is possible on ~2 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Rain High impact
Extreme rain Measures: Extreme rain days (>=50mm). Observed about 1% of days (0.2 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
0.2 days / month
- Share of days
- ~1% of days
- Upper edge
- Up to ~145mm (P95)
Why this matters
Extreme rain is possible on ~0 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Heat Moderate
Heatwave run Measures: Heatwave runs (>=3 hot days). Observed about 2.6 days/month in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
2.6 days / month
- Share of days
- —
- Upper edge
- Up to ~33°C (P95)
Why this matters
Heatwave runs are possible on ~3 days. Midday activity often needs adjustment around shade, hydration, and indoor fallback options.
Heat Moderate
Feels-like heatwave Measures: Feels-like heatwave runs (>=3 days). Observed about 1.3 days/month in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
1.3 days / month
- Share of days
- —
- Upper edge
- Up to ~41°C (P95)
Why this matters
Feels-like heatwave runs are possible on ~1 days. Midday activity often needs adjustment around shade, hydration, and indoor fallback options.
Visibility Moderate
Fog-likely signal Measures: Fog-likely visibility proxy. Observed about 4% of days (1.3 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
1.3 days / month
- Share of days
- ~4% of days
- Upper edge
- Up to ~93% (P95)
Why this matters
Fog-likely conditions are possible on ~1 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Heat Minor
Warm nights Measures: Warm nights (min >=22C). Observed about 100% of days (30.0 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
30.0 days / month
- Share of days
- ~100% of days
- Upper edge
- Up to ~26°C (P95)
Why this matters
Warm nights are possible on ~30 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Humidity Minor
Humid days Measures: Humid days (dew point >=18C). Observed about 100% of days (30.0 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
30.0 days / month
- Share of days
- ~100% of days
- Upper edge
- Up to ~25°C (P95)
Why this matters
Humid conditions are possible on ~30 days. Comfort and pace can drop quickly, so plan shorter outdoor blocks with air-conditioned backup stops.
Rain Minor
Wet days Measures: Wet days (>=0.1mm). Observed about 97% of days (29.1 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
29.1 days / month
- Share of days
- ~97% of days
- Upper edge
- Up to ~25mm (P95)
Why this matters
Measurable rain is possible on ~29 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Cloud Minor
Cloudy days Measures: Cloudy days (cloud cover >=60%). Observed about 94% of days (28.3 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
28.3 days / month
- Share of days
- ~94% of days
- Upper edge
- Up to ~100% (P95)
Why this matters
Cloudy skies are possible on ~28 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Rain Minor
Rainy hours Measures: Rain-hours signal (>=3h rain). Observed about 88% of days (26.5 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
26.5 days / month
- Share of days
- ~88% of days
- Upper edge
- Up to ~22h (P95)
Why this matters
Several rainy hours are possible on ~26 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Cloud Minor
Mostly cloudy days Measures: Mostly cloudy days (cloud cover >=80%). Observed about 81% of days (24.4 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
24.4 days / month
- Share of days
- ~81% of days
- Upper edge
- Up to ~100% (P95)
Why this matters
Mostly cloudy skies are possible on ~24 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Humidity Minor
High humidity Measures: High humidity days (RH >=80%). Observed about 77% of days (23.2 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
23.2 days / month
- Share of days
- ~77% of days
- Upper edge
- Up to ~90% (P95)
Why this matters
High humidity is possible on ~23 days. Comfort and pace can drop quickly, so plan shorter outdoor blocks with air-conditioned backup stops.
Rain Minor
Wet most of day Measures: Wet-most-of-day signal (>=6h rain). Observed about 71% of days (21.4 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
21.4 days / month
- Share of days
- ~71% of days
- Upper edge
- Up to ~23h (P95)
Why this matters
Wet-most-of-day conditions are possible on ~21 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Humidity Minor
Convective risk Measures: Convective storm risk proxy. Observed about 56% of days (16.8 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
16.8 days / month
- Share of days
- ~56% of days
- Upper edge
- Up to ~25°C (P95)
Why this matters
Convective risk signal appears on ~17 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Heat Minor
Hot nights Measures: Hot nights (min >=25C). Observed about 49% of days (14.7 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
14.7 days / month
- Share of days
- ~49% of days
- Upper edge
- Up to ~26°C (P95)
Why this matters
Hot nights are possible on ~15 days. Midday activity often needs adjustment around shade, hydration, and indoor fallback options.
Cloud Minor
Overcast days Measures: Overcast days (cloud cover >=95%). Observed about 48% of days (14.5 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
14.5 days / month
- Share of days
- ~48% of days
- Upper edge
- Up to ~100% (P95)
Why this matters
Overcast skies are possible on ~15 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Wind Minor
Gusty days Measures: Gusty days (>=40 km/h). Observed about 13% of days (3.8 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
3.8 days / month
- Share of days
- ~13% of days
- Upper edge
- Up to ~51km/h (P95)
Why this matters
Gusty conditions are possible on ~4 days. Exposed activities and transport links are more likely to be disrupted, so keep sheltered alternatives ready.
Other Minor
Low visibility proxy: same as fog-likely (RH ≥90% AND cloud ≥95%) — true visibility requires hourly visibility data Measures: Low visibility proxy: same as fog-likely (RH ≥90% AND cloud ≥95%) — true visibility requires hourly visibility data. Observed about 4% of days (1.3 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
1.3 days / month
- Share of days
- ~4% of days
- Upper edge
- Up to ~93 (P95)
Why this matters
Low visibility proxy: same as fog-likely (RH ≥90% AND cloud ≥95%) — true visibility requires hourly visibility data is possible on ~1 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Travel planning FAQ
Frequently asked questions
Quick answers to the weather questions you ask the most.
Is September a good time to visit Bangkok?
Typical September days in Bangkok reach highs of 31°C (88°F) with nights around 25°C (77°F). It usually feels hot by day and warm after dark. It is among the wetter months, so it is wise to have some indoor backup plans or flexible activities.
What are temperatures like in September?
Daytime temperatures in September typically peak near 31°C (88°F), while nights drop to around 25°C (77°F). Expect hot afternoons and warm evenings.
How much does it rain in September?
Rainfall in September averages 261 mm (10.3 in) across roughly 28 days. Overall it is a very wet time of year, so a light rain jacket and waterproof shoes are very handy.
How many hours of daylight are there in September?
You can expect about 12 hours of daylight in September. Sunrise is typically around 06:06 and sunset near 18:18. Daylight is fairly typical, with enough time for sightseeing.
How strong is the sun in September?
UV levels frequently reach very high levels (around 9), so strong sun protection is essential, especially around midday.
Is it windy in September?
In September, average wind speeds are around 8 km/h (5 mph), with gusts on the windiest days reaching about 41 km/h (25 mph). On the ground, it is it often feels breezy, especially in more exposed spots or along the coast.