The climate of Timor-Leste is characterized by extreme conditions. The country has a monsoon climate, which is typical for the Asian tropics. In the north of the country, there is little or no rain for almost eight months of the year. From December to March, northwest to southwest winds prevail, bringing the principal wet season for the year to most parts of the country. From May to October, southeast to northeast winds prevail, bringing mostly dry conditions, except on the south coast and the southern slopes where the wet season persists until July. There is little temperature variation on either a diurnal or a seasonal basis. Temperature variations mainly occur with altitude. Average annual temperatures decrease from 27°C at sea level to 24°C at 500 m; 21°C at 1000 m; 18°C at 1500 m and 14°C at 2000 m. Relative humidity varies between 70 and 80%, which makes the climate humid. Timor-Leste is influenced by El Nino and La Nina rainfalls. The average annual rainfall is around 1500 mm, varying from 565 mm at Manatuto along the northern coast to 2837 mm at Lolotai in the central-western mountains. Extremely heavy rainfall occasionally occurs in Timor-Leste during relatively short time intervals. Precipitation patterns are also influenced by the movement of the Inter-Tropical Convergence Zone. Key historical climate trends are summarized below:
- An analysis of global data by the IPCC shows that in the Timor-Leste region, temperature from 1901-2005 has increased 0.5-0.8°C over the century, while data for 1979-2005 suggests a lower decadal increase of 0.1-0.3°C with a mild acceleration over the later decades.
- Analysis of total rainfall in Timor-Leste indicates a reduction in mean annual rainfall from 1961-1990 as compared to the 1931-1960 period, the decrease being mostly felt in the December-February period.
This section provides the options to visualize historical climate data for different timeframes via map and annual cycle chart.