Bỉm Sơn weather in September

In September, Bỉm Sơn sees average daytime highs of 31°C and overnight lows near 25°C, with 278 mm of rain across 20.8 wet days and about 12.1 hours of daylight. It is the 5th-warmest and 2nd-wettest month of the year here.

Day-to-day highs hold fairly steady near 31°C through the month. The sky is clear or mostly clear about 17% of the time in September, and the air most often feels miserable.

Daylight stretches from about 12 h 24 min at the start of September to 11 h 48 min by month's end. Set against the rest of the year, September is Bỉm Sơn's 5th-clearest and 11th-windiest month. For the whole year in context, see Bỉm Sơn's year-round climate.

Daytime high
31°
5th warmest
Overnight low
25°
8th coldest
Rainfall
278 mm
20.8 wet days
Daylight
12 h 06 min
5:47 AM – 5:54 PM
Cloud cover
74%
5th clearest
Wind
7 km/h
11th windiest
Solar energy
4.27 kWh/m²
Travel score
3.2
out of 10

Bỉm Sơn is district-level town in Thanh Hóa province, Vietnam.

Density
802/km²
people per km²
Founded
1981

Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 31°C through the month.

A typical September day in Bỉm Sơn reaches about 31°C in the afternoon and slips back to 25°C overnight — a 6°C spread between the day's warmth and the night's chill. On most days the high lands between 28°C and 34°C. Set against its neighbours, September runs about 1°C cooler than August and about 2°C warmer than October.

20°25°30°35°151015202530
Avg high (°C)Avg low (°C)
13226
23226
33226
43226
53226
63226
73125
83125
93125
103125
113125
123125
133125
143125
153125
163125
173125
183125
193125
203125
213125
223125
233125
243124
253124
263124
273024
283024
293024
303024

How September really feels in Bỉm Sơn

Once humidity and wind are folded in, September averages 30 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
30
7 feel dangerously hot (≥ 39°C)
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.

Bỉm Sơn weather by month

How September compares with the rest of the year at a glance. September is the 5th-warmest and 2nd-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan21° / 15°295.610.96.7
Feb22° / 16°174.411.37.0
Mar25° / 19°356.711.97.0
Apr29° / 22°648.612.45.5
May32° / 25°17815.512.93.3
Jun34° / 27°17814.613.22.5
Jul33° / 27°23417.813.12.5
Aug32° / 26°3242312.72.6
Sep31° / 25°27820.812.13.2
Oct29° / 23°15614.511.55.1
Nov26° / 19°577.9116.9
Dec22° / 16°255.410.87.1

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 17% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 12% of September, with mostly cloudy or overcast conditions the remaining 71%. Skies tend to open up as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
11882
21882
31882
41882
51981
61981
72080
82080
92179
102179
112476
122476
132575
142674
152773
162971
173070
183169
193367
203367
213664
223763
233763
243862
254060
264060
274159
284159
294159
304357

Chance of precipitation in September

Any precipitation

Bỉm Sơn gets around 278 mm of rain over 20.8 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 70% and peaks near 82% on the wettest days. The odds ease toward the end of the month.

0%20%40%60%80%151015202530
Rain chance (%)
182
282
381
481
581
680
780
879
978
1077
1176
1274
1373
1472
1570
1669
1768
1866
1965
2064
2162
2261
2360
2460
2559
2659
2758
2858
2958
3057

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, September lands in the miserable band about 75% of days. Sticky, muggy-or-worse air turns up on roughly 99% of them.

0%25%50%75%100%151015202530
Humid (%)Muggy (%)Oppressive (%)Miserable (%)
100496
200595
300694
400694
511791
611890
711989
8111088
9121186
10121285
11121384
12131482
13131581
14141679
15141877
16141976
17152074
18162271
19162370
20172468
21172666
22282763
23282862
24292960
25293158
262103157
272103256
283113353
293123352
303133450

Wind in September

Winds average 7 km/h in September.

Across September, daily wind ranges from about 6 km/h on the calmest days to 8 km/h at its breeziest. It stays fairly steady from day to day.

051015151015202530
Wind speed (km/h)Feels
16calm
26calm
36calm
46calm
57calm
67calm
77calm
87calm
97calm
107calm
117calm
127calm
137calm
147calm
157calm
167calm
177calm
187calm
198calm
208calm
218calm
228calm
238calm
248calm
258calm
268calm
278calm
288calm
298calm
308calm

Sunrise & sunset in September

DaylightNight

Daylight runs from about 12 h 24 min at the start of September to 11 h 48 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 36 minutes over September. Sunrise moves from 5:44 AM to 5:51 AM, and sunset from 6:08 PM to 5:41 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.45:446:08
212.45:446:07
312.45:456:07
412.35:456:06
512.35:456:05
612.35:456:04
712.35:466:03
812.35:466:02
912.25:466:01
1012.25:466:00
1112.25:465:59
1212.25:475:58
1312.25:475:57
1412.25:475:56
1512.15:475:55
1612.15:475:54
1712.15:485:53
1812.15:485:52
1912.15:485:51
2012.05:485:50
2112.05:495:49
2212.05:495:49
2312.05:495:48
2412.05:495:47
2511.95:505:46
2611.95:505:45
2711.95:505:44
2811.95:505:43
2911.95:505:42
3011.85:515:41

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.27 kWh/m².

For context, solar energy here swings from a low near 2.43 kWh/m² to a high of 5.33 kWh/m² in June across the year — September's 4.27 kWh/m² falls in the middle.

012345151015202530
Solar energy (kWh/m²)Level
14.4Bright
24.4Bright
34.3Bright
44.3Bright
54.3Bright
64.3Bright
74.3Bright
84.3Bright
94.3Bright
104.2Bright
114.2Bright
124.2Bright
134.2Bright
144.2Bright
154.3Bright
164.3Bright
174.3Bright
184.3Bright
194.3Bright
204.3Bright
214.3Bright
224.3Bright
234.3Bright
244.3Bright
254.3Bright
264.3Bright
274.3Bright
284.3Bright
294.2Bright
304.2Bright
Planning a trip in September

Hazard calendar for Bỉm Sơn

In seasonPeak

In September, Bỉm Sơn sits inside its pacific typhoon and monsoon season. The full year is below, with each hazard's peak months called out.

Bỉm Sơn sits in the Pacific typhoon belt; the season peaks July–October.

Bỉm Sơn's monsoon runs May–October, when most of the year's rain falls.

Pacific typhoon
Monsoon
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

Is September a good time to visit Bỉm Sơn?

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

3.2
Sightseeing
9th-best month of the year
4.8
Beach & pool
9th-best month of the year

September is a weaker month for outdoor sightseeing in Bỉm Sơn.

What to pack for Bỉm Sơn in September

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

In September, Bỉm Sơn sees daytime highs around 31°C and nights near 25°C. Pack light clothes and rain gear. About 21 days see rain.

light clothesrain gear

Sea temperature near Bỉm Sơn 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 at the nearest coast (about 36 km away) is warmest in August at about 30°C and coldest in February near 20°C.

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

20°25°30°JanFebMarAprMayJunJulAugSepOctNovDeccoolrefreshingwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan21Refreshing
Feb20Refreshing
Mar21Refreshing
Apr24Refreshing
May28Warm
Jun29Tropical
Jul30Tropical
Aug30Tropical
Sep29Tropical
Oct28Warm
Nov26Warm
Dec23Refreshing

UV index in Bỉm Sơn in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 9 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Bỉm Sơn peaks around July 14 at about 12 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 15 at about 6 (high).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecVery highExtremeVery highHighJul 14UV 12Dec 15UV 6
UV index (midday)Level
Jan7Very high
Feb9Very high
Mar10Very high
Apr8Very high
May10Very high
Jun12Extreme
Jul12Extreme
Aug11Extreme
Sep9Very high
Oct9Very high
Nov7High
Dec6High

Air quality in Bỉm Sơn 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 Bỉm Sơn is worst in December — around 134 µg/m³ PM2.5 (unhealthy), about 3.8× the cleanest month (July, 35 µg/m³).

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

0306090120150JanFebMarAprMayJunJulAugSepOctNovDecUnhealthyPoorUnhealthyDec 20132 µg/m³Jul 1536 µg/m³
PM2.5 (µg/m³)Level
Jan126Unhealthy
Feb106Unhealthy
Mar94Unhealthy
Apr87Unhealthy
May60Unhealthy
Jun42Poor
Jul35Moderate
Aug46Poor
Sep69Unhealthy
Oct93Unhealthy
Nov116Unhealthy
Dec134Unhealthy
Location & terrain

Where is Bỉm Sơn?

Bỉm Sơn sits at 20.1°N, 105.9°E, 7 m above sea level, in Vietnam. The nearest listed city is Nga Sơn, 14 km away.

Topography around Bỉm Sơn

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

Within 3 km, the terrain around Bỉm Sơn has only modest variations in elevation — a maximum elevation change of 99 m around an average of 13 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 327 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,500 m.

The land around Bỉm Sơn is covered by trees (39%) and cropland (27%) within 3 km, trees (52%) and cropland (33%) within 16 km, and trees (41%), cropland (29%) and water (23%) within 80 km.

3 km
99 m
16 km
327 m
80 km
1,500 m
treesgrasslandcroplandartificial surfacesbare terrainwater
September weather nearby: Nga Sơn 14 km · Ninh Binh 24 km · Thanh Hóa 32 km · Sầm Sơn 39 km · Thị Trấn Lam Sơn 51 km · Nam Định 52 km · Phủ Lý 52 km · Thái Bình 65 km

Vietnam travel facts

Travel advisory
Level 1
Exercise Normal Precautions
Power plugs
Type A / B / C / F
220 V · 50 Hz
Prices
≈ 29% of US
price level, 2025
GDP per capita
$5,066
2025
Happiness
6.4 / 10
World Happiness, 2025
Safe drinking water
59%
of population, 2024
Homicide rate
1.5
per 100k, 2011
Road deaths
30.6
per 100k/yr, 2019
Income group
Upper middle
World Bank
English
Moderate
EF EPI 500
Religion
none 86%Catholic 6%Buddhist 6%Protestant 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 Bỉm Sơn (20.0781°, 105.8603°, elevation 7 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).