A transition to El Niño is highly likely, with over a 60% chance of its development between May and July 2026 in the Pacific, the Tonga Meteorological Services stated on its Climate & Ocean Outlook May-July 2026.
When El Niño conditions developed, we can expect disruptive weather and climate patterns, typically drier and warmer conditions.
Majority of the climate models, forecast the tropical Pacific to continue warming in the coming months.
However, both maximum and minimum temperatures are very likely to be above normal over the rest of Tonga, while near normal about Vava’u.
Below normal rainfall
The rainfall outlook for May - July generally indicates below normal for the forecast period.
The Wet Season, also called the Cyclone Season started on 1 November 2025 and will last till end of April 2026. On average, during this period Tonga receives average to above average rainfall.
The public are advised to collect water when it rains and use it wisely, this goes to all of Tonga islands but especially to Ha’apai, Vava’u and the Niuas.
Ocean update
Ocean temperatures around Tongatapu and ‘Eua will be 0.8 to 1.2 °C warmer than average.
Sea level height is forecast to be average to below average around Tonga waters.
Meanwhile, according to traditional knowledge indicators for Tropical Cyclone forecasting, there are no signs of cycloneat present.
