MetService is warning a line of thunderstorms over the sea may come onshore over Auckland on Monday night.
The storms are likely to be accompanied by wind gusts of up to 120km/h and large hail stones of up to 25 millimetres wide.
The forecaster says wind gusts of this strength can bring down trees and power lines and may make driving hazardous, while hail that size could damage glasshouses and vehicles.
