Waterspouts have been spotted in Auckland Harbour, following a storm alert issued for Waiheke Island earlier on Tuesday morning.
WeatherWatch advises Waiheke Island residents take extreme care, as the island is at risk of ground lighting, localised flooding and a chance of tornadoes.
Waterspouts have already been spotted near Whangaparaoa and across the Hauraki Gulf.
WeatherWatch spokesperson Philip Duncan says there is no risk to central Auckland at this time, as the storm is predicted to expand across the Hauraki Gulf.
MetService said the waterspouts are likely to be weak and were unlikely to come ashore.
Forecaster Georgina Griffiths said slow-moving thunderstorms will last until 11am.
Further thunderstorms are likely for Auckland on Tuesday afternoon, she said.