Yên Bái weather in September

In September, Yên Bái sees average daytime highs of 31°C and overnight lows near 25°C, with 229 mm of rain across 19.6 wet days and about 12.1 hours of daylight. It is the 5th-warmest and 5th-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 23% 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 Yên Bái's 4th-clearest and 8th-windiest month. For the whole year in context, see Yên Bái's year-round climate.

Daytime high
31°
5th warmest
Overnight low
25°
9th coldest
Rainfall
229 mm
19.6 wet days
Daylight
12 h 06 min
5:51 AM – 5:58 PM
Cloud cover
68%
4th clearest
Wind
4 km/h
8th windiest
Solar energy
4.23 kWh/m²
Travel score
3.3
out of 10

Yên Bái is provincial city in Yên Bái province, Vietnam.

Density
942/km²
people per km²

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 Yên Bái 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 3°C warmer than October.

20°25°30°35°151015202530
Avg high (°C)Avg low (°C)
13226
23226
33226
43226
53226
63226
73226
83225
93225
103225
113225
123125
133125
143125
153125
163125
173125
183125
193125
203125
213125
223125
233125
243125
253125
263124
273124
283024
293024
303024

How September really feels in Yên Bái

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.

Yên Bái weather by month

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

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan20° / 14°438.910.86.1
Feb21° / 16°337.311.36.5
Mar24° / 18°7010.511.86.4
Apr29° / 22°12613.112.55.1
May31° / 25°29420133.3
Jun32° / 26°39823.213.32.4
Jul32° / 26°40725.613.22.3
Aug32° / 26°4152512.72.5
Sep31° / 25°22919.612.13.3
Oct29° / 23°11512.511.55.4
Nov25° / 19°648117.0
Dec21° / 16°427.910.76.7

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 23% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 13% of September, with mostly cloudy or overcast conditions the remaining 64%. Skies tend to open up as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
12674
22674
32773
42773
52773
62773
72971
83070
93070
103268
113268
123268
133367
143466
153466
163763
173763
183862
194060
204159
214159
224357
234456
244555
254555
264654
274753
284852
294852
304852

Chance of precipitation in September

Any precipitation

Yên Bái gets around 229 mm of rain over 19.6 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 65% and peaks near 77% on the wettest days. The odds ease toward the end of the month.

0%20%40%60%80%151015202530
Rain chance (%)
177
277
377
476
576
675
775
874
973
1073
1172
1271
1370
1468
1567
1666
1764
1863
1962
2060
2159
2258
2357
2455
2555
2654
2753
2852
2951
3051

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 70% of days. Sticky, muggy-or-worse air turns up on roughly 100% of them.

0%25%50%75%100%151015202530
Humid (%)Muggy (%)Oppressive (%)Miserable (%)
100694
200793
300892
401990
5011089
6011188
7011287
8021385
9021583
10021682
11021781
12031879
13032077
14032176
15042373
16042472
17052669
18052768
19062965
20063163
21163360
22173458
23173656
24183853
25193951
261104149
271114246
281124344
291134442
301144540

Wind in September

Winds average 4 km/h in September.

Across September, daily wind ranges from about 4 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
14calm
24calm
34calm
44calm
54calm
64calm
74calm
84calm
94calm
104calm
114calm
124calm
134calm
144calm
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 5:47 AM to 5:55 AM, and sunset from 6:13 PM to 5:44 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.45:476:13
212.45:476:12
312.45:476:11
412.45:486:10
512.45:486:09
612.35:486:08
712.35:496:07
812.35:496:06
912.35:496:05
1012.35:496:04
1112.25:506:03
1212.25:506:02
1312.25:506:01
1412.25:506:00
1512.15:515:59
1612.15:515:58
1712.15:515:57
1812.15:525:56
1912.15:525:55
2012.05:525:54
2112.05:525:53
2212.05:535:52
2312.05:535:51
2412.05:535:50
2511.95:535:49
2611.95:545:48
2711.95:545:47
2811.95:545:46
2911.85:555:45
3011.85:555:44

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.23 kWh/m².

For context, solar energy here swings from a low near 2.19 kWh/m² to a high of 4.62 kWh/m² in June across the year — September's 4.23 kWh/m² falls in the middle.

012345151015202530
Solar energy (kWh/m²)Level
14.4Bright
24.4Bright
34.4Bright
44.3Bright
54.3Bright
64.3Bright
74.3Bright
84.3Bright
94.3Bright
104.3Bright
114.3Bright
124.3Bright
134.2Bright
144.2Bright
154.2Bright
164.2Bright
174.2Bright
184.2Bright
194.2Bright
204.2Bright
214.2Bright
224.2Bright
234.2Bright
244.1Bright
254.1Bright
264.1Bright
274.1Bright
284.1Bright
294.1Bright
304.1Bright
Planning a trip in September

Hazard calendar for Yên Bái

In seasonPeak

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

Yên Bái sits in the Pacific typhoon belt; the season peaks July–October.

Yên Bái's monsoon runs May–September, 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 Yên Bái?

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

3.3
Sightseeing
8th-best month of the year
5.0
Beach & pool
5th-best month of the year

September is a weaker month for outdoor sightseeing in Yên Bái.

What to pack for Yên Bái in September

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

In September, Yên Bái 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

UV index in Yên Bái in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 8 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Yên Bái peaks around June 22 at about 13 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near November 19 at about 5 (high).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecHighVery highVery highExtremeVery highHighJun 22UV 13Nov 19UV 5
UV index (midday)Level
Jan6High
Feb7High
Mar10Very high
Apr6High
May8Very high
Jun13Extreme
Jul12Extreme
Aug11Extreme
Sep8Very high
Oct7High
Nov5High
Dec6High

Air quality in Yên Bái 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 Yên Bái is worst in December — around 83 µg/m³ PM2.5 (unhealthy), about 2.9× the cleanest month (July, 29 µg/m³).

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

0306090JanFebMarAprMayJunJulAugSepOctNovDecUnhealthyPoorModeratePoorUnhealthyDec 2383 µg/m³Jul 2029 µg/m³
PM2.5 (µg/m³)Level
Jan83Unhealthy
Feb78Unhealthy
Mar78Unhealthy
Apr72Unhealthy
May50Poor
Jun36Poor
Jul29Moderate
Aug32Moderate
Sep42Poor
Oct57Unhealthy
Nov73Unhealthy
Dec83Unhealthy
Location & terrain

Where is Yên Bái?

Yên Bái sits at 21.7°N, 104.9°E, 45 m above sea level, in Vietnam. The nearest listed city is Tuyên Quang, 33 km away.

Topography around Yên Bái

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

Within 3 km, the terrain around Yên Bái has only modest variations in elevation — a maximum elevation change of 126 m around an average of 63 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 707 m; within 80 km, extreme variations in elevation — a maximum elevation change of 2,934 m.

The land around Yên Bái is covered by trees (79%) within 3 km, trees (80%) within 16 km, and trees (86%) within 80 km.

3 km
126 m
16 km
707 m
80 km
2,934 m
treesgrasslandcroplandartificial surfacesbare terrainwater
September weather nearby: Tuyên Quang 33 km · Nghĩa Lộ 43 km · Phú Thọ 48 km · Việt Trì 68 km · Cổ Đô 68 km · Thị Trấn Đại Từ 76 km · Thị Trấn Việt Quang 78 km · Bắc Quang 85 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 Yên Bái (21.7229°, 104.9113°, elevation 45 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). 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).