This page presents Lao PDR's climate context for the current climatology, 1991-2020, derived from observed, historical data. Information should be used to build a strong understanding of current climate conditions in order to appreciate future climate scenarios and projected change. You can visualize data for the current climatology through spatial variation, the seasonal cycle, or as a time series. Analysis is available for both annual and seasonal data. Data presentation defaults to national-scale aggregation, however sub-national data aggregations can be accessed by clicking within a country, on a sub-national unit. Other historical climatologies can be selected from the Time Period dropdown list. Data for specific coordinates can be downloaded for in the Data Download page.
Lao PDR is characterized by a tropical climate, influenced by the southeast monsoon which brings 70% of annual rainfall and high humidity. There are two distinct seasons: the rainy season, or monsoon, from May to mid-October and the dry season from mid-October to April. Average rainfall can be as high as 3,000 millimeters (mm) per year. Mean annual temperatures of 20°C was observed in the northern and eastern mountainous areas and the plateaus, whereas temperatures are higher in the plains at 25-27°C.
Based on the country’s altitude, Lao PDR can be divided into three different climatic zones. The northern mountainous areas above 1,000 m have a montane temperate and hilly sub-tropical climate. Here, temperature ranges are lower than the rest of the country. The central mountainous areas in the Annamite Chain vary in altitude between 500 to 1,000 m and are characterized by a tropical monsoonal climate with high temperatures and average rainfall totals. More than 50% of the population lives in the tropical lowland plain and floodplains along the Mekong River and its main tributaries. Temperature and precipitation rates have been shown to be sensitive to El Niño Southern Oscillation (ENSO), but generally to a lesser extent when compared to other Southeast Asian nations.