Normally, you can expect the weather in Vientiane in September is 25 with a general average high of 31 and low around 23. We have provided a clearer breakdown here:
| Month | Degrees Celsius |
|---|---|
| Temperature | 25 |
| High Temperature | 31 |
| Low Temperature | 23 |
Useful Links: Vientiane Weather: Average Weather & Yearly Climate