Diễn Thành weather in September

In September, Diễn Thành sees average daytime highs of 31°C and overnight lows near 25°C, with 293 mm of rain across 19.9 wet days and about 12.1 hours of daylight. It is the 5th-warmest and 1st-wettest month of the year here.

Highs ease over the month, from about 32°C in the first days to 30°C by the end. 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 Diễn Thành's 8th-clearest and 12th-windiest month. For the whole year in context, see Diễn Thành's year-round climate.

Daytime high
31°
5th warmest
Overnight low
25°
8th coldest
Rainfall
293 mm
19.9 wet days
Daylight
12 h 06 min
5:49 AM – 5:55 PM
Cloud cover
76%
8th clearest
Wind
7 km/h
12th windiest
Solar energy
4.41 kWh/m²
Travel score
3.2
out of 10

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 32°C in the first days to 30°C by the end.

A typical September day in Diễn Thành 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 2°C cooler than August and about 3°C warmer than October.

20°25°30°35°40°151015202530
Avg high (°C)Avg low (°C)
13226
23226
33226
43226
53226
63226
73226
83226
93226
103125
113125
123125
133125
143125
153125
163125
173125
183125
193125
203125
213125
223125
233125
243125
253025
263024
273024
283024
293024
303024

How September really feels in Diễn Thành

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
9 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.

Diễn Thành weather by month

How September compares with the rest of the year at a glance. September is the 5th-warmest and 1st-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan21° / 16°173.9117.0
Feb23° / 17°133.311.47.4
Mar26° / 19°315.311.97.2
Apr30° / 23°496.912.45.3
May33° / 26°1151412.93.1
Jun35° / 28°1161213.12.1
Jul34° / 28°17114.2132.3
Aug33° / 27°25920.512.62.6
Sep31° / 25°29319.912.13.2
Oct29° / 23°23817.511.64.8
Nov26° / 20°629.111.16.7
Dec22° / 17°265.110.97.2

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 72%. Skies tend to open up as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
11882
21882
31882
42080
52080
62080
72080
82278
92278
102476
112476
122674
132674
142773
152773
162971
172971
183070
193268
203268
213367
223367
233664
243664
253763
263664
273763
283862
293961
303961

Chance of precipitation in September

Any precipitation

Diễn Thành gets around 293 mm of rain over 19.9 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 72% on the wettest days. The odds ease toward the end of the month.

0%20%40%60%80%151015202530
Rain chance (%)
172
272
372
471
571
671
771
870
970
1070
1170
1269
1369
1469
1568
1668
1767
1866
1966
2065
2164
2264
2364
2464
2564
2664
2764
2864
2964
3064

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 74% of days. Sticky, muggy-or-worse air turns up on roughly 99% of them.

0%25%50%75%100%151015202530
Humid (%)Muggy (%)Oppressive (%)Miserable (%)
100892
200991
300991
4011089
5011089
6011188
7011188
8021286
9021286
10021385
11031483
12031582
13031681
14041779
15141877
16141976
17152074
18152173
19152371
20152569
21152668
22162865
23163063
24163162
25173359
26273457
27283555
28283654
29293752
302103850

Wind in September

Winds average 7 km/h in September, the calmest month.

Across September, daily wind ranges from about 7 km/h on the calmest days to 8 km/h at its breeziest. It stays fairly steady from day to day.

0246810151015202530
Wind speed (km/h)Feels
17calm
27calm
37calm
47calm
57calm
67calm
77calm
87calm
97calm
107calm
117calm
127calm
137calm
147calm
157calm
167calm
177calm
187calm
197calm
207calm
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 5:46 AM to 5:51 AM, and sunset from 6:09 PM to 5:42 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.45:466:09
212.45:466:08
312.35:466:07
412.35:476:06
512.35:476:05
612.35:476:04
712.35:476:03
812.35:476:02
912.25:476:02
1012.25:486:01
1112.25:486:00
1212.25:485:59
1312.25:485:58
1412.15:485:57
1512.15:495:56
1612.15:495:55
1712.15:495:54
1812.15:495:53
1912.15:495:52
2012.05:495:51
2112.05:505:50
2212.05:505:50
2312.05:505:49
2412.05:505:48
2511.95:505:47
2611.95:515:46
2711.95:515:45
2811.95:515:44
2911.95:515:43
3011.85:515:42

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.41 kWh/m².

For context, solar energy here swings from a low near 2.47 kWh/m² to a high of 5.73 kWh/m² in June across the year — September's 4.41 kWh/m² falls in the middle.

024151015202530
Solar energy (kWh/m²)Level
14.7Bright
24.7Bright
34.7Bright
44.6Bright
54.6Bright
64.6Bright
74.5Bright
84.5Bright
94.5Bright
104.5Bright
114.4Bright
124.4Bright
134.4Bright
144.4Bright
154.4Bright
164.4Bright
174.3Bright
184.3Bright
194.3Bright
204.3Bright
214.3Bright
224.3Bright
234.3Bright
244.3Bright
254.2Bright
264.2Bright
274.2Bright
284.2Bright
294.1Bright
304.1Bright
Planning a trip in September

Hazard calendar for Diễn Thành

In seasonPeak

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

Diễn Thành sits in the Pacific typhoon belt; the season peaks July–October.

Diễn Thành'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 Diễn Thành?

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

3.2
Sightseeing
8th-best month of the year
4.8
Beach & pool
8th-best month of the year

September is a weaker month for outdoor sightseeing in Diễn Thành.

What to pack for Diễn Thành in September

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

In September, Diễn Thành sees daytime highs around 31°C and nights near 25°C. Pack light clothes and rain gear. About 20 days see rain.

light clothesrain gear

Sea temperature near Diễn Thành 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
Mar22Refreshing
Apr24Warm
May28Warm
Jun30Tropical
Jul30Tropical
Aug30Tropical
Sep30Tropical
Oct28Warm
Nov26Warm
Dec23Refreshing

UV index in Diễn Thành in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 11 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Diễn Thành peaks around July 17 at about 12 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 14 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 17UV 12Dec 14UV 6
UV index (midday)Level
Jan8Very high
Feb9Very high
Mar10Very high
Apr9Very high
May11Extreme
Jun12Extreme
Jul12Extreme
Aug12Extreme
Sep11Extreme
Oct10Very high
Nov7High
Dec6High

Air quality in Diễn Thành 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 Diễn Thành is worst in April — around 62 µg/m³ PM2.5 (unhealthy), about 3.5× the cleanest month (July, 18 µg/m³).

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

020406080JanFebMarAprMayJunJulAugSepOctNovDecPoorUnhealthyPoorModeratePoorApr 1161 µg/m³Jul 1618 µg/m³
PM2.5 (µg/m³)Level
Jan52Poor
Feb52Poor
Mar57Unhealthy
Apr62Unhealthy
May35Poor
Jun20Moderate
Jul18Moderate
Aug21Moderate
Sep30Moderate
Oct41Poor
Nov47Poor
Dec52Poor
Location & terrain

Where is Diễn Thành?

Diễn Thành sits at 19.0°N, 105.6°E, 9 m above sea level, in Vietnam. The nearest listed city is Kim Liên, 32 km away.

Topography around Diễn Thành

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

Within 3 km, the terrain around Diễn Thành has only modest variations in elevation — a maximum elevation change of 12 m around an average of 3 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 430 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,711 m.

The land around Diễn Thành is covered by cropland (44%) and artificial surfaces (21%) within 3 km, water (35%), cropland (33%) and trees (20%) within 16 km, and trees (54%) and water (28%) within 80 km.

3 km
12 m
16 km
430 m
80 km
1,711 m
treesgrasslandcroplandartificial surfacesbare terrainwatermangroves
September weather nearby: Kim Liên 32 km · Hoàng Mai 35 km · Vinh 35 km · Yên Vinh 35 km · Bến Thủy 38 km · Nghi Xuân 39 km · Nghi Sơn 45 km · Hồng Lĩnh 51 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 Diễn Thành (18.9765°, 105.6003°, elevation 9 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).