Climatology
This page presents Sri Lanka'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.
Observed, historical data is produced by the Climatic Research Unit (CRU) of University of East Anglia. Data is presented at a 0.5º x 0.5º (50km x 50km) resolution.
Sri Lanka has two main seasons, the Maha season associated with the northeast monsoon (September – March) and the Yala season associated with the southwest monsoon (May – August). With an average temperature of around 27 - 28°C, Sri Lanka is one of the hottest countries in the world. Sri Lanka’s commercial capital, Colombo, experiences average temperatures of 28 - 29°C and, like much of the rest of the country, has little monthly variation in temperature. Daily maximum temperatures average around 31°C all year round. The most important factor affecting temperature variations within Sri Lanka is altitude, with considerably low temperatures experienced in its south-central mountain ranges. Sri Lanka’s precipitation regime is divided into three zones: the wet zone, intermediate zone, and dry zone. The wet zone, found in the southwest, receives a mean annual rainfall of over 2,500 mm, with a strong contribution from the southwest monsoon. The dry zones, found in the south and northwest, receive less than 1,750 mm. The intermediate zones found in the eastern and central regions, receive between 1,750 mm and 2,500 mm, primarily from the northeast monsoon. Areas of the southwest slopes of the central hills are known to experience as much as 5,000 mm in a year and annual rainfall can vary by more than 1,000 – 2,000 mm over distances of less than 100 km. All regions receive steady rainfall during the inter-monsoon seasons.