Tonga is the second most at-risk country in the world in terms of exposure to natural hazards. Tropical cyclones are the most likely and consistent threat for Tonga, but other common hazards include earthquakes, tsunamis, floods and volcanic eruptions. The recent Hunga Tonga–Hunga Ha’apai undersea volcano erupted on 15 January 2022 has caused economic damage of USD 90.4 million. From the last 40 years, 70 tropical cyclones passed by Tonga, with most occurring between November and April which total cumulative damages of USD 246 million. In 2018, Tropical Cyclone Gita, one of the costliest disasters in Tonga nearly 80,000 people were affected. During Tropical Cyclone Ian in 2014, almost 70% of the inhabitants of Tonga’s Ha’apai island group i.e., around 5,500 people were affected and caused an economic loss of USD 50 million. Moreover, flooding from heavy rainfall along with cyclonic storms occurs every four or five years in the country; numerous events within recent years which demonstrate flood prone areas. Tonga is prone to drought conditions, major droughts occurred in 1983, 1998, and 2006.

The coastal nature of settlement patterns in the country exposes communities and infrastructure to a high degree of impact from sea level rise, storm surges and coastal flooding. In addition to this, Tongatapu is a low-lying coral atoll, with the highest point only 65 metres above sea level at the south-eastern part of the island. The capital Nuku’alofa is only 1–2 metres above sea level and the major port facilities are likely to be under serious threat if sea level rises as predicted.