Early this morning Cyclone Winston was located about 230 kilometres south of Niuatoputapu, or 80 kilometres north-northeast of Neiafu - moving at about 23 kilometres an hour, with gusts of up to 150 kilometres an hour.
The category two cyclone has already caused some minor damage and flooding of low-lying areas in Tongatapu and Ha'apai.
A staff member at the National Emergency Management Office says a team will conduct a survey of the islands this morning to determine if any further damage was caused overnight.