Vientiane Prefecture weather in September

September is one of the least pleasant months in Vientiane Prefecture: highs of 30°C (86°F) and about 204 mm (8.0 in) of rain on average. Nights average 23°C (74°F) and cloud cover 84% (NASA POWER, 2001–2025 averages). It is the 2nd wettest month of the year and the 6th coolest. Compared with August, it is about as warm and drier; October brings highs of 30°C (85°F) and 85 mm (3.3 in) of rain.

Figures are long-term averages for Vientiane, the largest city in Vientiane Prefecture. See below for other places.

Is September a good time to visit Vientiane Prefecture?

least pleasant month Weather score 49/100.

September is one of the least pleasant months for weather in Vientiane Prefecture. For better conditions, consider Nov–Feb.

See Vientiane Prefecture's sky and forecast now

Does it rain a lot in Vientiane Prefecture in September?

Yes, it is one of the rainy months: about 204 mm (8.0 in) falls in an average September. It is the 2nd wettest month of the year.

How warm is Vientiane Prefecture in September?

Days average 30°C (86°F) and nights 23°C (74°F).

Vientiane Prefecture weather by month

Month	High	Low	Rain	Cloud	Weather
January	28°C (83°F)	15°C (58°F)	8 mm	33%	best
February	32°C (89°F)	18°C (64°F)	13 mm	33%	best
March	35°C (95°F)	21°C (71°F)	35 mm	47%	fair
April	37°C (98°F)	24°C (76°F)	61 mm	58%	fair
May	34°C (93°F)	25°C (76°F)	168 mm	82%	least pleasant
June	32°C (89°F)	24°C (75°F)	170 mm	90%	least pleasant
July	31°C (87°F)	24°C (74°F)	203 mm	92%	least pleasant
August	30°C (86°F)	23°C (74°F)	246 mm	93%	least pleasant
September	30°C (86°F)	23°C (74°F)	204 mm	84%	least pleasant
October	30°C (85°F)	21°C (70°F)	85 mm	59%	fair
November	29°C (83°F)	18°C (64°F)	16 mm	40%	best
December	27°C (80°F)	15°C (58°F)	6 mm	32%	best

Sources: 2001–2025 monthly averages from NASA POWER (MERRA-2 reanalysis). Page updated Oct 31, 2026. How we rate months