WEATHER · CLIMATE NORMALS · 1991–2020
Vientiane Climate — Averages by Month
What the weather in Vientiane, LAaverages across a standard 30-year period. Each month's figure is the 1991–2020 mean temperature and total rainfall from the ERA5 reanalysis — the long-run normal a place settles around, not a forecast for any particular day.
Month-by-month normals
| Month | Avg temperature | Avg rainfall |
|---|---|---|
| January | 22.3 °C · coldest | 10.6 mm |
| February | 24.4 °C | 15.6 mm |
| March | 27.2 °C | 33.4 mm |
| April | 29.2 °C · warmest | 70.8 mm |
| May | 28.8 °C | 256.2 mm |
| June | 28.5 °C | 322.4 mm |
| July | 28.0 °C | 387.9 mm |
| August | 27.7 °C | 417.1 mm · wettest |
| September | 27.7 °C | 300.4 mm |
| October | 27.0 °C | 97.2 mm |
| November | 25.0 °C | 20.1 mm |
| December | 22.4 °C | 8.8 mm |
How to read these numbers
These are reanalysis normals, not readings from a single weather station. They come from the ERA5 0.25° (~25 km) global reanalysis grid, sampled at the grid cell nearest Vientiane — centred at 18.00°N, 102.75°E. A reanalysis blends observations with a physics model onto an even grid, so a coastal or mountain city's cell can read a little cooler, warmer, wetter or drier than the city centre itself. The month-to-month shape — when it's hot, when it rains — is what these normals capture best.
“Normal” means the 1991–2020 average, the current World Meteorological Organization standard period. A normal is what a place tends toward over decades — any single day, month or year can and will depart from it.