Extraordinarily heavy rainfall in southern Tonga during October smashed a national record and in ‘Eua the flash flooding coincided with extreme high tides.
In their latest Climate Outlook 2024 Tonga Meteorological Services reported that during heavy rain on 19 October ‘Eua received 355.00mm of rainfall in 24 hours. At the same time, Fua’amotu recorded 222.00mm of rainfall in 24 hours.
“This is the highest October [daily] rainfall ever recorded in the whole of Tonga,” said Tonga Met.
The previous daily rainfall record during October was 210mm in Niuafo’ou in 2017.
The islands of Tongatapu and ‘Eua were most affected by the unseasonal deluge.
“Heavy rain on 19 October caused flooding of low-lying areas and coastal areas [were] impacted by inundation from extreme high tides mainly in Tongatapu and ‘Eua causing damage to infrastructure and residentials.”
Tonga MET said that the extreme high tide from 18-19 October was also a factor that resulted in the flooding of some coastal areas.
Low-lying and coastal areas that were affected included Popua, Fasi, Fanga, Ma’ufanga, Ngele’ia, Pili and Fanga-o-Pilolevu.
Monthly rainfall
During October, Tonga Met said that Tongatapu, ‘Eua and Niuatoputapu met with above average rainfall, while Vava’u and Ha’apai was received below average rainfall.
For the whole month of October ‘Eua recorded significantly above average rainfall of 587.6mm (compared to 128.5mm for the previous month, September).
For the whole month of October the capital Nuku’alofa recorded significantly above average rainfall of 387.0mm (compared to 64mm for the previous month, September).
National rainfall records
Vava’u still holds the record for the highest rainfall in 24 hours for Tonga, 397.7mm recorded on 23 January 2000, but that was during the height of the rainy season. Meteorological records started there in 1995.
Fua'amotu started recording rainfall in Tonga in 1981 and Niuafo'ou in 1971.
Outlook for December-January
Tonga Met said that the rainfall outlook over December 2024 to February 2025 is consistent with rainfall patterns experienced during past La Niñas.
- Average to above average rainfall is predicted for December and December 2024 to February 2025.
- Warmer than average air temperature.
- Sea surface temperature outlook is predicted to be 24oC about south of Tonga and increase northwards
- towards the Niuas.
- Sea level forecast shows average heights across most of Tonga wasters except for the southern Tonga waters, which shows 30-60mm above average.
