MetService yesterday predicted more waterspouts and funnel clouds could be on the way, issuing a severe thunderstorm watch for Northland, Waikato, Waitomo, Taumaranui, Bay of Plenty, Rotorua, Taupo and Taranaki.
A swarm of waterspouts spotted in Auckland's Waitemata Harbour on Wednesday sent Twitter and social media users into a frenzy.
Mr McDavitt said they could reappear because the weather system that brought them remained in place.
"Warm, moist air, combined with converging winds in the lower levels of the atmosphere, and day time heating,'' he said. "If you hear thunder, seek shelter.''