A rain deficit is forecast for the coming months as the impacts of an El Niño take hold across the region.
In the last three months, the rainfall in Tongatapu has been below average.
Local media report that until December, Tongatapu, Vava'u, Ha'apai, and 'Eua, should expect 30 percent less rainfall than usual. Niuafo'ou and Niuatoputapu are forecast to receive 20 percent less.
The public has been urged to use rainwater and tap water efficiently, in order to conserve supplies.