Tonga faces a forecast of two to four tropical cyclones during the 2026–27 season, alongside below-average rainfall and prolonged drought conditions. The outlook also gives a moderate to high chance of at least one severe tropical cyclone, with the greatest cyclone risk expected from January to March 2027.
Tonga Meteorological Services set out the assessment in its “Tropical Cyclone Outlook for Tonga 2026–2027”, dated 28 October 2026. The release places the cyclone forecast alongside a rainfall outlook and drought declarations, warnings and alerts covering different parts of Tonga.
The rainfall forecast covers November 2026 to January 2027. A developing very strong El Niño is expected to peak by December 2026 and prolong drought conditions, according to the service’s outlook.
Cyclone risk highest early in 2027
The two-to-four cyclone estimate applies to systems expected to affect Tonga during the season. The assessment of a moderate to high chance of at least one severe tropical cyclone is a separate indication of the potential severity of the season.
The service identifies January, February and March 2027 as the highest-risk period. That places the peak cyclone risk in the new year, later than the forecast December 2026 peak of the developing El Niño and partly overlapping the rainfall forecast.
January is included in both forecast windows: it is the final month of the November-to-January period of expected below-average rainfall and the first month of the January-to-March period of highest cyclone risk. February and March fall outside that stated rainfall window.
The cyclone estimate and severe-cyclone probability remain forecasts. Two to four systems are expected to affect Tonga, while the prospect of at least one severe cyclone is expressed as a moderate to high chance, rather than a certainty.
Drought declarations remain in force
Drought declarations remain in force for Tongatapu, ʻEua, Haʻapai and Niuatoputapu. Vavaʻu remains under a drought warning, while Niuafo’ou is under a drought alert. Those are the statuses set out in the service’s release.
The outlook therefore describes different drought statuses across the six named areas. Four are covered by declarations, while the other two are under a warning and an alert respectively; they are not presented as being under the same designation.
For rainfall, the forecast is below average over the three-month period from November 2026 to January 2027. That assessment concerns expected rainfall during those months, while the declarations, warning and alert describe the drought status recorded in the October release.
The service links the prospect of prolonged drought conditions to the developing very strong El Niño. Its expected peak by December 2026 falls within the rainfall outlook period, which begins in November and continues into January of the following year.
The December timing is a forecast for the peak of El Niño, not an end date for drought. The release says the developing event is expected to prolong drought conditions, alongside its forecast of below-average rainfall into January 2027.
The outlook brings together two distinct concerns: the continuation of drought conditions and the possibility of tropical cyclones, including a severe system. The higher cyclone risk from January to March is separate from the November-to-January rainfall assessment, although the two periods overlap.
Together, the forecast periods put January 2027 at the intersection of the two outlooks. For Tonga, the service’s assessment is of below-average rainfall extending into that month and the highest cyclone-risk period beginning then and continuing through March.
