Sầm Sơn weather in September

In September, Sầm Sơn sees average daytime highs of 29°C and overnight lows near 26°C, with 368 mm of rain across 20.2 wet days and about 12.1 hours of daylight. It is the 4th-warmest and 1st-wettest month of the year here.

Day-to-day highs hold fairly steady near 29°C through the month. The sky is clear or mostly clear about 25% 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 Sầm Sơn's 5th-clearest and 12th-windiest month. For the whole year in context, see Sầm Sơn's year-round climate.

Daytime high
29°
4th warmest
Overnight low
26°
9th coldest
Rainfall
368 mm
20.2 wet days
Daylight
12 h 06 min
5:47 AM – 5:54 PM
Cloud cover
69%
5th clearest
Wind
14 km/h
12th windiest
Solar energy
4.43 kWh/m²
Travel score
4.1
out of 10

Sầm Sơn is city in Thanh Hóa province.

Density
2,888/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 29°C through the month.

A typical September day in Sầm Sơn reaches about 29°C in the afternoon and slips back to 26°C overnight — a 3°C spread between the day's warmth and the night's chill. On most days the high lands between 27°C and 31°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)
13027
23027
33027
42927
52927
62927
72927
82927
92927
102927
112927
122927
132927
142926
152926
162926
172926
182926
192926
202926
212926
222926
232926
242926
252926
262826
272826
282826
292826
302826

How September really feels in Sầm Sơn

Once humidity and wind are folded in, September averages 29 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
29
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.

Sầm Sơn weather by month

How September compares with the rest of the year at a glance. September is the 4th-warmest and 1st-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan19° / 17°5510.610.95.9
Feb20° / 18°368.411.36.1
Mar22° / 20°529.711.96.4
Apr25° / 23°627.512.47.0
May28° / 26°13912.212.95.5
Jun30° / 28°1461113.24.3
Jul30° / 28°21212.713.14.2
Aug30° / 28°31220.112.73.7
Sep29° / 26°36820.212.14.1
Oct27° / 24°24116.211.55.7
Nov24° / 22°829.911.16.9
Dec21° / 18°548.910.86.5

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 25% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 10% of September, with mostly cloudy or overcast conditions the remaining 65%. Skies tend to open up as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
12476
22476
32476
42377
52476
62575
72575
82575
92773
102872
112872
123070
133268
143367
153466
163565
173664
183862
194060
204159
214258
224258
234456
244456
254555
264753
274753
284852
294852
304852

Chance of precipitation in September

Any precipitation

Sầm Sơn gets around 368 mm of rain over 20.2 wet days in September, the wettest month. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 68% and peaks near 73% on the wettest days. The odds ease toward the end of the month.

0%20%40%60%80%151015202530
Rain chance (%)
173
273
373
473
573
673
773
872
972
1072
1171
1271
1370
1470
1569
1669
1768
1867
1966
2065
2164
2264
2363
2462
2562
2661
2761
2860
2960
3059

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 71% of days. Sticky, muggy-or-worse air turns up on roughly 99% of them.

0%25%50%75%100%151015202530
Humid (%)Muggy (%)Oppressive (%)Miserable (%)
100694
200793
300892
401990
5011089
6011188
7111187
8121285
9121384
10121483
11131581
12131680
13141778
14141976
15152074
16152173
17162370
18162469
19172666
20172864
21182962
22183160
23183358
24193456
251103653
262103751
272113849
282114047
292124145
302134243

Wind in September

Winds average 14 km/h in September, the calmest month.

Across September, daily wind ranges from about 13 km/h on the calmest days to 15 km/h at its breeziest. It stays fairly steady from day to day.

05101520151015202530
Wind speed (km/h)Feels
113light breeze
213light breeze
313light breeze
413light breeze
513light breeze
613light breeze
713light breeze
813light breeze
913light breeze
1013light breeze
1113light breeze
1213light breeze
1314light breeze
1414light breeze
1514light breeze
1614light breeze
1714light breeze
1814light breeze
1914light breeze
2014light breeze
2114light breeze
2215light breeze
2315light breeze
2415light breeze
2515light breeze
2615light breeze
2715light breeze
2815light breeze
2915light breeze
3015light breeze

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 5:50 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
312.45:456:06
412.35:456:05
512.35:456:04
612.35:456:03
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
1412.15:475:56
1512.15:475:55
1612.15:475:54
1712.15:485:53
1812.15:485:52
1912.15:485:51
2012.05:485:50
2112.05:485:49
2212.05:495:48
2312.05:495:47
2412.05:495:46
2511.95:495:46
2611.95:505:45
2711.95:505:44
2811.95:505:43
2911.95:505:42
3011.85:505:41

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.43 kWh/m².

For context, solar energy here swings from a low near 2.6 kWh/m² to a high of 5.55 kWh/m² in May across the year — September's 4.43 kWh/m² falls in the middle.

024151015202530
Solar energy (kWh/m²)Level
14.6Bright
24.5Bright
34.5Bright
44.5Bright
54.5Bright
64.5Bright
74.4Bright
84.4Bright
94.4Bright
104.4Bright
114.4Bright
124.4Bright
134.4Bright
144.4Bright
154.4Bright
164.4Bright
174.4Bright
184.4Bright
194.4Bright
204.4Bright
214.4Bright
224.4Bright
234.4Bright
244.4Bright
254.4Bright
264.4Bright
274.4Bright
284.4Bright
294.4Bright
304.4Bright
Planning a trip in September

Hazard calendar for Sầm Sơn

In seasonPeak

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

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

Sầm Sơn's monsoon runs July–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 Sầm Sơn?

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

4.1
Sightseeing
11th-best month of the year
5.2
Beach & pool
7th-best month of the year

September is a reasonable time to visit Sầm Sơn for sightseeing.

What to pack for Sầm Sơn in September

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

In September, Sầm Sơn sees daytime highs around 29°C and nights near 26°C. Pack light clothes and rain gear. About 20 days see rain.

light clothesrain gear

Sea temperature near Sầm Sơn in September

The nearest coast averages about 30°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 August at about 30°C and coldest in February near 21°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
Feb21Refreshing
Mar21Refreshing
Apr24Refreshing
May28Warm
Jun29Tropical
Jul30Tropical
Aug30Tropical
Sep30Tropical
Oct28Warm
Nov26Warm
Dec23Refreshing

UV index in Sầm Sơn in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 10 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Sầm Sơn peaks around August 11 at about 12 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 16 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 highHighAug 11UV 12Dec 16UV 6
UV index (midday)Level
Jan7Very high
Feb9Very high
Mar10Very high
Apr9Very high
May10Extreme
Jun12Extreme
Jul12Extreme
Aug13Extreme
Sep10Very high
Oct9Very high
Nov7Very high
Dec6High

Air quality in Sầm 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 Sầm Sơn is worst in April — around 65 µg/m³ PM2.5 (unhealthy), about 3.3× the cleanest month (July, 20 µg/m³).

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

020406080JanFebMarAprMayJunJulAugSepOctNovDecUnhealthyPoorModeratePoorUnhealthyApr 1065 µg/m³Jul 1920 µg/m³
PM2.5 (µg/m³)Level
Jan65Unhealthy
Feb63Unhealthy
Mar63Unhealthy
Apr65Unhealthy
May43Poor
Jun25Moderate
Jul20Moderate
Aug23Moderate
Sep33Moderate
Oct46Poor
Nov55Poor
Dec64Unhealthy
Location & terrain

Where is Sầm Sơn?

Sầm Sơn sits at 19.7°N, 105.9°E, 10 m above sea level, in Vietnam. The nearest listed city is Thanh Hóa, 16 km away.

Topography around Sầm Sơn

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

Within 3 km, the terrain around Sầm Sơn has only modest variations in elevation — a maximum elevation change of 78 m around an average of 3 m above sea level; within 16 km, only modest variations in elevation — a maximum elevation change of 176 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,500 m.

The land around Sầm Sơn is covered by water (58%) within 3 km, water (60%) within 16 km, and trees (39%), water (33%) and cropland (22%) within 80 km.

3 km
78 m
16 km
176 m
80 km
1,500 m
treesgrasslandcroplandartificial surfacesbare terrainwater
September weather nearby: Thanh Hóa 16 km · Nga Sơn 31 km · Bỉm Sơn 39 km · Nghi Sơn 46 km · Thị Trấn Lam Sơn 55 km · Hoàng Mai 55 km · Ninh Binh 59 km · Nam Định 83 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 Sầm Sơn (19.7333°, 105.9°, elevation 10 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).