Country

Tonga

Explore historical and projected climate data, climate data by sector, impacts, key vulnerabilities and what adaptation measures are being taken. Explore the overview for a general context of how climate change is affecting Tonga.

Climate Data Historical

Tonga’s climate is tropical and is defined by a wet season from November to April with moderate and variable rainfall, and a dry season from May to October. The wettest months are January, February, and March with precipitation exceeding 250 mm of rainfall per month. During the dry season, precipitation per month is less than 250 mm. The mean annual temperature in Tonga varies from 26°C to 23°C. During the wet season, the average temperature ranges from 25–26°C, whereas during the dry season the average temperature ranges from 21-24°C. Climate in Tonga and this portion of the Pacific in general is governed by a number of factors, which include the trade winds and the movement of the South Pacific Convergence Zone (SPCZ), a zone of high-pressure rainfall that migrates across the Pacific south of the equator. Year-to-year variability in climate is also strongly influenced by the El Niño Southern Oscillation (ENSO) in the south-east Pacific, which can bring prolonged drought conditions and contribute to a depletion of potable water, and tropical cyclones that occur during the wet season, causing extensive damage to local infrastructure, agriculture, and major food sources. Key historical climate trends are summarized below:

Temperature

  • Mean temperatures have increased by 0.4–0.8°C since 1970, with warming most rapid in the warmest season (November–April).   
  • The frequency of hot days and hot nights has increased significantly across the Pacific.

Precipitation

  • Spatially selected meteorological stations throughout Tonga show a general decrease in annual rainfall in central and southern parts of Tonga since 1970.

This section provides the options to visualize historical climate data for different timeframes via map and annual cycle chart.

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Click on map to change chart data from country aggregated to site-specific data.