Climatology
This page presents Samoa'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.
Samoa’s climate is typical of that associated with small tropical islands, and is characterized by high rainfall and humidity, near-uniform temperatures throughout the year, winds dominated by the south-easterly trade winds (which are directly associated with the South Pacific Convergence Zone), and the occurrence of tropical cyclones during the southern-hemisphere summer. There are two seasons, marked by significant differences in rainfall: Samoa’s wet season lasts from November to April and its dry season starts in May and ends in October. The annual rainfall total is about 3,000 mm (varying from 2,500 mm in the northwest parts of the main islands to over 6,000 mm in the highlands of Savai’i), and about 75% of the precipitation occurs between November and February. Samoa’s topography has a significant effect on rainfall distribution – because of a predominant easterly wind, the mountain ranges determine the distribution of rainfall. Wet areas are generally those located in the southeast and the relatively drier areas are located in the northwest. Samoa is also vulnerable to anomalously long dry spells that coincide with the El Niño Southern Oscillation (ENSO). The temperature in Samoa is typically tropical (ranging from 24°C-32°C daily) and generally constant during the entire year with little seasonal variation due to Samoa’s near-equatorial location. Observations from the Meteorological Office at Mulinu’u have revealed that the highest mean temperature of 27.1°C occurs between December and March, while the lowest mean temperature of 26.0°C occurs between July and September.