What may have been the eye of Cyclone Rene is thought to have passed over the Tonga capital Nuku'alofa earlier tonight.
Our reporter says it went completely still for around ten minutes after a sustained period of wind, and then the wind resumed, but from the opposite direction.
The deputy director the National Disaster Office, Male'u Takai says it may be the worst storm in 50 years, though that would need to be assessed after first light.
Rene, which has been downgraded to a category three cyclone, is still forecast to carry sustained winds of 155 kilometres an hour and momentary gusts as strong as 230 kilometres.
It is coinciding with a high tide and flooding of low lying areas is expected.
People had been advised to seek higher ground and our reporter has said soldiers may be brought into forcibly remove people if flooding is severe.
Meanwhile the police commissioner Chris Kelley says he has already seen some damage around the capital.
"I have seen trees down, coconut trees across power lines. I have seen trees across the roa. I have seen sheets of metal flying. I know that at the police headquarters we have certainly sustained some damage to our buildings."