Bo weather in September

In September, Bo sees average daytime highs of 30°C and overnight lows near 24°C, with 290 mm of rain across 21.1 wet days and about 12.1 hours of daylight. It is the 5th-warmest and 3rd-wettest month of the year here.

Day-to-day highs hold fairly steady near 30°C through the month. The sky is clear or mostly clear about 18% 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 Bo's 5th-clearest and 9th-windiest month. For the whole year in context, see Bo's year-round climate.

Daytime high
30°
5th warmest
Overnight low
24°
9th coldest
Rainfall
290 mm
21.1 wet days
Daylight
12 h 06 min
5:49 AM – 5:56 PM
Cloud cover
74%
5th clearest
Wind
5 km/h
9th windiest
Solar energy
4.19 kWh/m²
Travel score
3.6
out of 10

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 30°C through the month.

A typical September day in Bo reaches about 30°C in the afternoon and slips back to 24°C overnight — a 6°C spread between the day's warmth and the night's chill. On most days the high lands between 26°C and 33°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)
13125
23025
33025
43024
53024
63024
73024
83024
93024
103024
113024
123024
133024
143024
153024
163024
173024
183024
193024
203024
213024
223023
232923
242923
252923
262923
272923
282923
292923
302923

How September really feels in Bo

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
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.

Bo weather by month

How September compares with the rest of the year at a glance. September is the 5th-warmest and 3rd-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan19° / 14°448.510.96.0
Feb21° / 15°287.211.36.3
Mar24° / 18°5910.411.96.4
Apr28° / 21°11413.512.55.3
May31° / 24°27520.2133.4
Jun32° / 26°26721.113.22.7
Jul32° / 26°32023.613.12.7
Aug31° / 25°39326.412.72.7
Sep30° / 24°29021.112.13.6
Oct27° / 21°15614.711.55.6
Nov24° / 18°668.2117.0
Dec21° / 14°356.310.86.8

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 18% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 11% 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 (%)
11783
21783
31882
41882
51882
61882
72080
82080
92080
102179
112377
122377
132575
142773
152872
162872
173070
183169
193268
203367
213565
223565
233664
243862
253961
263961
274060
284159
294159
304258

Chance of precipitation in September

Any precipitation

Bo gets around 290 mm of rain over 21.1 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 85% on the wettest days. The odds ease toward the end of the month.

0%20%40%60%80%100%151015202530
Rain chance (%)
185
285
384
484
583
683
782
881
980
1079
1177
1276
1375
1473
1572
1670
1769
1867
1966
2064
2163
2262
2361
2460
2560
2659
2758
2858
2957
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 49% of days. Sticky, muggy-or-worse air turns up on roughly 98% of them.

0%25%50%75%100%151015202530
Comfortable (%)Humid (%)Muggy (%)Oppressive (%)Miserable (%)
10012277
20012376
30012574
40012673
50122869
60122968
70123166
80133264
90133462
100143560
110143659
120253855
130253954
140264052
150274150
160284248
170294346
1802104444
1902114542
2002124640
2103134738
2203144836
2303144934
2403155131
2504165129
2604165327
2705175325
2805175523
2916185421
3017185519

Wind in September

Winds average 5 km/h in September.

Across September, daily wind ranges from about 5 km/h on the calmest days to 6 km/h at its breeziest. It stays fairly steady from day to day.

0246810151015202530
Wind speed (km/h)Feels
15calm
25calm
35calm
45calm
55calm
65calm
75calm
85calm
95calm
105calm
115calm
125calm
135calm
145calm
155calm
165calm
175calm
186calm
196calm
206calm
216calm
226calm
236calm
246calm
256calm
266calm
276calm
286calm
296calm
306calm

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 5:45 AM to 5:52 AM, and sunset from 6:10 PM to 5:42 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.45:456:10
212.45:456:09
312.45:466:08
412.45:466:07
512.35:466:06
612.35:466:05
712.35:476:04
812.35:476:03
912.35:476:02
1012.25:476:02
1112.25:486:01
1212.25:486:00
1312.25:485:59
1412.25:485:58
1512.15:485:57
1612.15:495:56
1712.15:495:55
1812.15:495:54
1912.15:495:53
2012.05:505:52
2112.05:505:51
2212.05:505:50
2312.05:505:49
2412.05:515:48
2511.95:515:47
2611.95:515:46
2711.95:515:45
2811.95:525:44
2911.95:525:43
3011.85:525:42

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.19 kWh/m².

For context, solar energy here swings from a low near 2.25 kWh/m² to a high of 4.97 kWh/m² in June across the year — September's 4.19 kWh/m² falls in the middle.

012345151015202530
Solar energy (kWh/m²)Level
14.3Bright
24.2Bright
34.2Bright
44.2Bright
54.2Bright
64.2Bright
74.2Bright
84.2Bright
94.1Bright
104.1Bright
114.1Bright
124.1Bright
134.2Bright
144.2Bright
154.2Bright
164.2Bright
174.2Bright
184.2Bright
194.2Bright
204.2Bright
214.2Bright
224.2Bright
234.2Bright
244.2Bright
254.2Bright
264.2Bright
274.2Bright
284.2Bright
294.2Bright
304.2Bright
Planning a trip in September

Hazard calendar for Bo

In seasonPeak

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

Bo'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 Bo?

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

3.6
Sightseeing
8th-best month of the year
4.9
Beach & pool
6th-best month of the year

September is a weaker month for outdoor sightseeing in Bo.

What to pack for Bo in September

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

In September, Bo sees daytime highs around 30°C and nights near 24°C. Pack light clothes and rain gear. About 21 days see rain.

light clothesrain gear

UV index in Bo in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 7 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Bo peaks around June 20 at about 11 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near November 22 at about 6 (high).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecHighVery highHighExtremeVery highHighJun 20UV 11Nov 22UV 6
UV index (midday)Level
Jan6High
Feb7High
Mar9Very high
Apr6High
May7High
Jun12Extreme
Jul10Extreme
Aug10Extreme
Sep7High
Oct8Very high
Nov6High
Dec6High

Air quality in Bo 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 Bo is worst in December — around 171 µg/m³ PM2.5 (very unhealthy), about 3.4× the cleanest month (July, 50 µg/m³).

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

0306090120150180JanFebMarAprMayJunJulAugSepOctNovDecVery unhealthyUnhealthyPoorUnhealthyVery unhealthyDec 19170 µg/m³Jul 1452 µg/m³
PM2.5 (µg/m³)Level
Jan161Very unhealthy
Feb136Unhealthy
Mar122Unhealthy
Apr106Unhealthy
May76Unhealthy
Jun59Unhealthy
Jul50Poor
Aug68Unhealthy
Sep96Unhealthy
Oct125Unhealthy
Nov152Very unhealthy
Dec171Very unhealthy
Location & terrain

Where is Bo?

Bo sits at 20.7°N, 105.5°E, 67 m above sea level, in Vietnam. The nearest listed city is Xuân Mai, 26 km away.

Topography around Bo

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

Within 3 km, the terrain around Bo has significant variations in elevation — a maximum elevation change of 427 m around an average of 122 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 1,185 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,622 m.

The land around Bo is covered by trees (71%) and cropland (23%) within 3 km, trees (86%) within 16 km, and trees (60%) and cropland (27%) within 80 km.

3 km
427 m
16 km
1,185 m
80 km
1,622 m
treesgrasslandcroplandartificial surfaceswater
September weather nearby: Xuân Mai 26 km · Hòa Bình 26 km · Phủ Lý 42 km · Hà Đông 42 km · Dại Mỗ 42 km · Vinhomes Smart City 43 km · Tây Mỗ 43 km · Thanh Liệt 44 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 Bo (20.6726°, 105.5362°, elevation 67 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).