Lai Châu weather in September

In September, Lai Châu sees average daytime highs of 27°C and overnight lows near 20°C, with 201 mm of rain across 22.2 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 27°C through the month. The sky is clear or mostly clear about 14% of the time in September, and the air most often feels muggy.

Daylight stretches from about 12 h 30 min at the start of September to 11 h 48 min by month's end. Set against the rest of the year, September is Lai Châu's 9th-clearest and 11th-windiest month. For the whole year in context, see Lai Châu's year-round climate.

Daytime high
27°
5th warmest
Overnight low
20°
9th coldest
Rainfall
201 mm
22.2 wet days
Daylight
12 h 06 min
5:57 AM – 6:04 PM
Cloud cover
72%
9th clearest
Wind
3 km/h
11th windiest
Solar energy
4.38 kWh/m²
Travel score
4.5
out of 10

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 27°C through the month.

A typical September day in Lai Châu reaches about 27°C in the afternoon and slips back to 20°C overnight — a 7°C spread between the day's warmth and the night's chill. On most days the high lands between 24°C and 29°C. Set against its neighbours, September runs on par with August and about 2°C warmer than October.

15°20°25°30°151015202530
Avg high (°C)Avg low (°C)
12821
22821
32821
42821
52821
62821
72821
82821
92821
102721
112720
122720
132720
142720
152720
162720
172720
182720
192720
202720
212720
222720
232720
242720
252720
262720
272720
282719
292619
302619

Lai Châu 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
Jan18° / 10°631010.85.9
Feb20° / 11°539.411.26.4
Mar24° / 14°10613.811.86.5
Apr26° / 17°13618.712.55.4
May27° / 20°22224.413.14.3
Jun28° / 21°32528.513.33.4
Jul27° / 22°38929.513.23.4
Aug28° / 21°37128.712.83.5
Sep27° / 20°20122.212.14.5
Oct25° / 18°961511.56.0
Nov22° / 14°508.710.96.9
Dec19° / 11°497.410.76.5

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 14% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 15% of September, with mostly cloudy or overcast conditions the remaining 71%. Skies tend to open up as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
12377
22476
32377
42377
52476
62476
72476
82476
92476
102575
112575
122575
132674
142674
152773
162773
172872
182872
192971
203169
213268
223367
233466
243763
253763
263862
273961
283961
294060
304159

Chance of precipitation in September

Any precipitation

Lai Châu gets around 201 mm of rain over 22.2 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 74% 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
284
384
483
582
682
781
880
980
1079
1179
1278
1377
1476
1576
1675
1774
1873
1972
2071
2170
2269
2367
2466
2565
2663
2762
2860
2959
3058

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

Most of September feels muggy — the stacked bands show each day's mix of comfort levels, read off the dew point.

By dew point, September lands in the muggy band about 69% of days. Sticky, muggy-or-worse air turns up on roughly 85% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
10026731
20026731
30036730
40036829
50046828
60056926
70156925
80166924
90177022
100177121
110187219
120197218
130297316
1402107315
1502117314
1603127312
1703127411
1804137211
1904147210
2004157110
210515719
220516709
230617689
240618688
250619678
260720658
270721657
281723636
291724626
301725625

Wind in September

Winds average 3 km/h in September.

Across September, daily wind ranges from about 3 km/h on the calmest days to 3 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
153calm
163calm
173calm
183calm
193calm
203calm
213calm
223calm
233calm
243calm
253calm
263calm
273calm
283calm
293calm
303calm

Sunrise & sunset in September

DaylightNight

Daylight runs from about 12 h 30 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 42 minutes over September. Sunrise moves from 5:52 AM to 6:01 AM, and sunset from 6:19 PM to 5:50 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.55:526:19
212.45:536:19
312.45:536:18
412.45:536:17
512.45:536:16
612.35:546:15
712.35:546:14
812.35:546:13
912.35:556:12
1012.35:556:10
1112.25:556:09
1212.25:566:08
1312.25:566:07
1412.25:566:06
1512.15:566:05
1612.15:576:04
1712.15:576:03
1812.15:576:02
1912.15:586:01
2012.05:586:00
2112.05:585:59
2212.05:585:58
2312.05:595:57
2412.05:595:56
2511.95:595:55
2611.96:005:54
2711.96:005:53
2811.96:005:52
2911.86:015:51
3011.86:015:50

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.38 kWh/m².

For context, solar energy here swings from a low near 2.66 kWh/m² to a high of 4.99 kWh/m² in April across the year — September's 4.38 kWh/m² falls in the middle.

012345151015202530
Solar energy (kWh/m²)Level
14.5Bright
24.5Bright
34.5Bright
44.5Bright
54.5Bright
64.5Bright
74.5Bright
84.5Bright
94.5Bright
104.5Bright
114.5Bright
124.5Bright
134.4Bright
144.4Bright
154.4Bright
164.4Bright
174.4Bright
184.4Bright
194.3Bright
204.3Bright
214.3Bright
224.3Bright
234.3Bright
244.3Bright
254.2Bright
264.2Bright
274.2Bright
284.2Bright
294.2Bright
304.1Bright
Planning a trip in September

Hazard calendar for Lai Châu

In seasonPeak

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

Lai Châu'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 Lai Châu?

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

4.5
Sightseeing
8th-best month of the year
4.6
Beach & pool
5th-best month of the year

September is a reasonable time to visit Lai Châu for sightseeing.

What to pack for Lai Châu in September

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

In September, Lai Châu sees daytime highs around 27°C and nights near 20°C. Pack light clothes and rain gear. About 22 days see rain.

light clothesrain gear

UV index in Lai Châu 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 Lai Châu peaks around June 19 at about 14 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 19 at about 5 (high).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecVery highExtremeVery highExtremeVery highHighJun 19UV 14Dec 19UV 5
UV index (midday)Level
Jan7High
Feb9Very high
Mar11Extreme
Apr9Very high
May11Extreme
Jun14Extreme
Jul13Extreme
Aug12Extreme
Sep10Very high
Oct9Very high
Nov8Very high
Dec5High

Air quality in Lai Châu 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 Lai Châu is worst in April — around 70 µg/m³ PM2.5 (unhealthy), about 5.0× the cleanest month (July, 14 µg/m³).

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

020406080JanFebMarAprMayJunJulAugSepOctNovDecModeratePoorUnhealthyModerateApr 1367 µg/m³Jul 1814 µg/m³
PM2.5 (µg/m³)Level
Jan25Moderate
Feb33Moderate
Mar54Poor
Apr70Unhealthy
May28Moderate
Jun15Moderate
Jul14Moderate
Aug15Moderate
Sep18Moderate
Oct22Moderate
Nov23Moderate
Dec25Moderate
Location & terrain

Where is Lai Châu?

Lai Châu sits at 22.4°N, 103.5°E, 919 m above sea level, in Vietnam. The nearest listed city is Sapa, 40 km away.

Thị Trấn Thuận ChâuÍt OngDien Bien PhuSơn La

Topography around Lai Châu

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

Within 3 km, the terrain around Lai Châu has significant variations in elevation — a maximum elevation change of 544 m around an average of 1,001 m above sea level; within 16 km, extreme variations in elevation — a maximum elevation change of 2,836 m; within 80 km, extreme variations in elevation — a maximum elevation change of 3,035 m.

The land around Lai Châu is covered by trees (43%) and grassland (32%) within 3 km, trees (74%) within 16 km, and trees (85%) within 80 km.

3 km
544 m
16 km
2,836 m
80 km
3,035 m
treesgrasslandcroplandartificial surfaceswater
September weather nearby: Sapa 40 km · Lào Cai 54 km · Mường Lay 55 km · Thị Trấn Phố Lu 75 km · Thị Trấn Thuận Châu 109 km · Ít Ong 114 km · Dien Bien Phu 121 km · Sơn La 128 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 Lai Châu (22.3964°, 103.4582°, elevation 919 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).