Dien Bien Phu weather in September

In September, Dien Bien Phu sees average daytime highs of 28°C and overnight lows near 21°C, with 199 mm of rain across 21.5 wet days and about 12.1 hours of daylight. It is the 4th-warmest and 4th-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 12% of the time in September, and the air most often feels oppressive.

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 Dien Bien Phu's 9th-clearest and 12th-windiest month. For the whole year in context, see Dien Bien Phu's year-round climate.

Daytime high
28°
4th warmest
Overnight low
21°
9th coldest
Rainfall
199 mm
21.5 wet days
Daylight
12 h 06 min
5:59 AM – 6:06 PM
Cloud cover
75%
9th clearest
Wind
3 km/h
12th windiest
Solar energy
4.41 kWh/m²
Travel score
4.4
out of 10

Dien Bien Phu is city in Điện Biên, Vietnam.

Density
1,317/km²
people per km²
Founded
1992

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 28°C through the month.

A typical September day in Dien Bien Phu reaches about 28°C in the afternoon and slips back to 21°C overnight — a 7°C spread between the day's warmth and the night's chill. On most days the high lands between 25°C and 30°C. Set against its neighbours, September runs on par with August and about 2°C warmer than October.

15°20°25°30°35°151015202530
Avg high (°C)Avg low (°C)
12822
22822
32822
42821
52821
62821
72821
82821
92821
102821
112821
122821
132821
142821
152821
162821
172821
182821
192821
202821
212821
222821
232821
242821
252821
262820
272820
282820
292820
302820

Dien Bien Phu weather by month

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

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan22° / 11°35510.87.5
Feb24° / 12°254.811.37.9
Mar27° / 16°558.611.86.9
Apr29° / 19°11515.412.55.1
May29° / 21°19522.2133.8
Jun28° / 22°32327.313.33.2
Jul28° / 22°40328.913.23.4
Aug28° / 22°36828.312.73.4
Sep28° / 21°19921.512.14.4
Oct26° / 19°7211.511.56.3
Nov24° / 15°335.5117.7
Dec22° / 12°294.510.77.6

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 12% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 14% of September, with mostly cloudy or overcast conditions the remaining 74%. Skies tend to open up as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
11684
21684
31882
41882
51882
61882
71981
81981
91981
102080
112080
122179
132278
142278
152476
162476
172575
182773
192872
202971
213268
223268
233466
243565
253763
263862
273961
284060
294159
304357

Chance of precipitation in September

Any precipitation

Dien Bien Phu gets around 199 mm of rain over 21.5 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 71% and peaks near 86% on the wettest days. The odds ease toward the end of the month.

0%20%40%60%80%100%151015202530
Rain chance (%)
186
286
385
484
583
682
781
880
979
1079
1178
1277
1376
1474
1573
1672
1771
1870
1969
2067
2166
2264
2363
2461
2560
2658
2756
2855
2953
3052

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 61% of days. Sticky, muggy-or-worse air turns up on roughly 95% of them.

0%25%50%75%100%151015202530
Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
1001486
2001585
3011683
4011881
5011980
6012178
7012277
8012475
9012574
10022672
11022870
12022969
13023167
14033265
15033463
16043561
17043660
18043858
19053956
20054055
21064153
22074251
23074448
24084546
25094744
261104841
271115039
281125136
291125334
301135432

Wind in September

Winds average 3 km/h in September, the calmest month.

Across September, daily wind ranges from about 3 km/h on the calmest days to 4 km/h at its breeziest. It stays fairly steady from day to day.

0246810151015202530
Wind speed (km/h)Feels
13calm
23calm
33calm
43calm
53calm
63calm
73calm
83calm
93calm
103calm
113calm
123calm
133calm
143calm
154calm
164calm
174calm
184calm
194calm
204calm
214calm
224calm
234calm
244calm
254calm
264calm
274calm
284calm
294calm
304calm

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 5:55 AM to 6:02 AM, and sunset from 6:21 PM to 5:52 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.45:556:21
212.45:556:20
312.45:556:19
412.45:556:18
512.35:566:17
612.35:566:16
712.35:566:15
812.35:576:14
912.35:576:13
1012.25:576:12
1112.25:576:11
1212.25:586:10
1312.25:586:09
1412.25:586:08
1512.15:586:07
1612.15:596:06
1712.15:596:05
1812.15:596:04
1912.15:596:03
2012.06:006:02
2112.06:006:01
2212.06:006:00
2312.06:005:59
2412.06:015:58
2511.96:015:57
2611.96:015:56
2711.96:025:55
2811.96:025:54
2911.86:025:53
3011.86:025:52

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 3.4 kWh/m² to a high of 5.44 kWh/m² in April across the year — September's 4.41 kWh/m² falls in the middle.

012345151015202530
Solar energy (kWh/m²)Level
14.3Bright
24.3Bright
34.3Bright
44.3Bright
54.3Bright
64.3Bright
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
234.5Bright
244.5Bright
254.5Bright
264.5Bright
274.5Bright
284.4Bright
294.4Bright
304.4Bright
Planning a trip in September

Hazard calendar for Dien Bien Phu

In seasonPeak

In September, Dien Bien Phu sits inside its monsoon season. The full year is below, with each hazard's peak months called out.

Dien Bien Phu's monsoon runs May–September, when most of the year's rain falls.

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

Is September a good time to visit Dien Bien Phu?

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

4.4
Sightseeing
8th-best month of the year
4.8
Beach & pool
9th-best month of the year

September is a reasonable time to visit Dien Bien Phu for sightseeing.

What to pack for Dien Bien Phu in September

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

In September, Dien Bien Phu sees daytime highs around 28°C and nights near 21°C. Pack light clothes and rain gear. About 22 days see rain.

light clothesrain gear

UV index in Dien Bien Phu 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 Dien Bien Phu peaks around August 12 at about 14 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 19 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 highExtremeVery highHighAug 12UV 14Dec 19UV 6
UV index (midday)Level
Jan7Very high
Feb9Very high
Mar11Extreme
Apr9Very high
May10Extreme
Jun14Extreme
Jul13Extreme
Aug14Extreme
Sep10Very high
Oct9Very high
Nov8Very high
Dec6High

Air quality in Dien Bien Phu 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 Dien Bien Phu is worst in April — around 303 µg/m³ PM2.5 (very unhealthy), about 32.6× the cleanest month (August, 9 µg/m³).

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

0306090120150180210240270300JanFebMarAprMayJunJulAugSepOctNovDecModerateUnhealthyVery unhealthyUnhealthyGoodModerateApr 15276 µg/m³Aug 109 µg/m³
PM2.5 (µg/m³)Level
Jan20Moderate
Feb37Poor
Mar107Unhealthy
Apr303Very unhealthy
May53Poor
Jun11Good
Jul10Good
Aug9Good
Sep11Good
Oct15Moderate
Nov17Moderate
Dec19Moderate
Location & terrain

Where is Dien Bien Phu?

Dien Bien Phu sits at 21.4°N, 103.0°E, 485 m above sea level, in Vietnam. The nearest listed city is Mường Lay, 69 km away.

Sơn LaNong KhiawÍt OngLai ChâuMuang XaySapa

Topography around Dien Bien Phu

How much the land rises and falls, and what covers it, within 3, 16 and 80 km of Dien Bien Phu.

Within 3 km, the terrain around Dien Bien Phu has significant variations in elevation — a maximum elevation change of 255 m around an average of 505 m above sea level; within 16 km, very significant variations in elevation — a maximum elevation change of 1,307 m; within 80 km, very significant variations in elevation — a maximum elevation change of 2,010 m.

The land around Dien Bien Phu is covered by trees (36%), cropland (30%) and artificial surfaces (24%) within 3 km, trees (62%) and grassland (23%) within 16 km, and trees (79%) within 80 km.

3 km
255 m
16 km
1,307 m
80 km
2,010 m
treesgrasslandcroplandartificial surfacesbare terrainwater
September weather nearby: Mường Lay 69 km · Thị Trấn Thuận Châu 69 km · Sơn La 93 km · Nong Khiaw 100 km · Ít Ong 105 km · Lai Châu 121 km · Muang Xay 133 km · Sapa 136 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 Dien Bien Phu (21.386°, 103.023°, elevation 485 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. 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).