A prolonged indentation in sea levels is being blamed for causing damaging elevated high tides in the Cook Islands, both Samoas and French Polynesia.
A scientist at New Zealand's National Institute of Water and Atmospheric Research (NIWA) Connon Andrews said it's a common phenomenon although the intensity of such events are being exacerbated by sea level rising.
Photo: Cook Islands News
"The issue is that it's just a very strong event that coincides with high tides, but with climate change, of course, there is an increase in sea levels that will exacerbate the indentation going forward.
"It consistently happens all the time. There's no real seasonality to it, the issue is that it's just a very strong event that coincides with high tides."
Both the Cook Islands and American Samoa declared a state of emergency, after the unusually tides flooded properties and damaged infrastructure.
A wave alert is in place for Rarotonga and all southern group islands in the Cook Islands until Thursday local time.
All foreshore properties are being asked to be prepared for waves to reach heights of up to 5 metres.
Officials say people in southern areas between Avana and Aroa should monitor forecasts and conditions closely and remove or keep a close eye on all equipment on beaches and within the lagoon.
The swells have disrupted tourism in the Cook Islands, prompting the government to provide financial aid to affected businesses.
High waves in Samoa linked to climate change says forecaster
A severe weather warning remains in place for Samoa after the swells flooded coastal areas of the eastern and south coasts of the country.
Samoan meteorological services expect swell heights to remain between 2.5m and 3m but are expecting conditions to ease over the weekend.
Leading forecaster Aloali'i Liu said the unusual phenomenon is linked to climate change.
"I believe there is an effect of climate change as of now. Although it is happening within the dry season which is something that is a very rare occasion however, there was an event that was like this recently in 2018."
Airports around French Polynesia shut due to safety concerns
French Polynesian domestic flights are being disrupted after seven atolls shut their airports.
For safety reasons, internal flights must be routed within an hour's flying time of the nearest airport, should there be an emergency.
This caused a return flight from Tahiti to Mangareva in the Gambier Islands - about 1600km away - to be cancelled as the airport on Tureia in the Tuamotus could not be used.
Meanwhile, many families affected by coastal flooding have been relying on churches for help.
The government has started a fund to compensate those most affected by the waves, however the community services have been providing basic needs.
A priest from a church in the southwest district of Maiaeta on Tahiti told La Premiere they've been providing food.
"The district authorities have sent us a list of families that we could help out.
"This morning (Tuesday) we received five families that needed our help and we will see five others in Papeari.
"There has been some people who have approached the church to give money directly, and these payments are being used for food donations."