Mekong River Basin Rainfall in Average Year

The river basin experiences a complex rainfall pattern. The river’s source in the Tibetan plateau receives little rainfall and snow/glacier melt is the main source of freshwater into the river’s upper reaches. As it travels downstream the influence of the monsoon is prevalent. The majority of rain falls in the lower reaches of the basin, particularly in the eastern and northern highlands. There is seasonality to the rainfall with May-June often being the start of the wettest months and November to April the drier period. The river ends in a large delta which, during the dry season, is subject to tidal inundation as the sea water protrudes up river at high tide during this period of low flow.

Average Total Rainfall (mm/yr)

Bargraph referencing the colours on the rainfall maps.

Other Mekong Maps

Mekong Rainfall Maps