Almost half a year's worth of rain fell on Ha'apai in one month, causing a sinkhole on Holopeka Road, Lifuka on Sunday, 30 December.

The sinkhole was filled in the next day by the Ministry of Infrastructure.

While the average rainfall for the month of December in the group is 133ml, Tonga's Director of Meteorology, ‘Ofa Fa’anunu said that last December 700ml of rain fell in Ha’apai.

“The annual average rainfall in that area is 1600ml,” he said.

Climate Officer Selu Finau-Lahi said the amount of rain that fell in Ha'apai was the highest in recorded history for the month of December.

However, she said the highest rainfall on record was in January 2012 when 786ml of rain fell over the group.

Tonga is currently in its rainy season and the rain is not likely to ease up. It is also cyclone season and already a number of low pressure systems have been tracking through the Pacific. 

Tropical Cyclone Mona, which was upgrade to Category 2 this morning, is expected to move over Fiji during the weekend. At this stage, projected tracks show it might bypass Tonga.