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.

Country Summary

This page presents high-level information for Tonga's climate zones and its seasonal cycle for mean temperature and precipitation for the latest climatology, 1991-2020. Climate zone classifications are derived from the Köppen-Geiger climate classification system, which divides climates into five main climate groups divided based on seasonal precipitation and temperature patterns. The five main groups are A (tropical), B (dry), C (temperate), D (continental), and E (polar). All climates except for those in the E group are assigned a seasonal precipitation sub-group (second letter).  Climate classifications are identified by hovering your mouse over the legend. A narrative overview of Tonga's country context and climate is provided following the visualizations.


Köppen-Geiger Climate Classification, 1991-2020
  • Af
  • Am
  • As/Aw
  • BWh
  • BWk
  • BSh
  • BSk
  • Csa
  • Csb
  • Csc
  • Cwa
  • Cwb
  • Cwc
  • Cfa
  • Cfb
  • Cfc
  • Dsa
  • Dsb
  • Dsc
  • Dsd
  • Dwa
  • Dwb
  • Dwc
  • Dwd
  • Dfa
  • Dfb
  • Dfc
  • Dfd
  • ET
  • EF

The Kingdom of Tonga is an archipelago consisting of four clusters of 172 coral and volcanic islands with a total area of 747 square kilometres (km2), located in the Central South Pacific Ocean. Tonga is situated at the subduction zone of the Indian-Australian and the Pacific tectonic plates and lies within the Ring of Fire where intense seismic activities occur. The islands are formed on the tops of two parallel submarine ridges stretching from Southwest to Northeast and enclosing a 50 km wide trough. Most of the islands in Tonga originate from coral line, and some islands are of volcanic origin. The majority of these islands are comparatively flat except for those raised by tectonic action. Several volcanoes, some of which are still active, exist along the western ridge, while many coral islands have formed along the eastern ridge, amongst them are the Vava’u and Ha’apai island groups. Coral islands are in two categories, the low and raised coral islands

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 mean annual temperature in Tonga varies from 23°C to 26°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.

As of 2019, Tonga’s population was estimated at nearly 104,500 people over 18,005 households – about 74% of the total population resides on the largest island of Tongatapu (at 260 km2). Tonga enjoys a relatively strong position as a lower middle-income country, in part due to its high migration and remittance culture. Tonga continues to rely on current transfers (workers’ remittances and government transfers) to support household and government consumption. It is estimated that about 50% of all Tongans live overseas and their remittances represent approximately 50–60%2 of gross national domestic income.

The economy of Tonga is highly dependent on climate sensitive sectors such agriculture, fisheries and tourism and a limited resource base that is sensitive to external shocks. According to Tonga’s latest available statistics, in 2015–16 the service sector contribution to GDP (including tourism trade, and hospitality, and as measured in current prices) was 54.5%, while agriculture contributed 14.7% to GDP in current prices. Increased local market production and export of fruit and vegetables including the main crop, squash, as well as kava, yams, and sweet potatoes, contributed to an increasing value of agriculture in the year of estimation. The agricultural sector supports the majority of the population for subsistence and for cash income, employing a third of the labour force and accounting for at least 50% of the export earnings. The gross value-added of fishing activities increased from 7.4% of GDP in 2014–15 to 15.6% in 2015–16, largely as a result of increasing exports which includes prepared and preserved fish and seaweed.