Heavy showers and isolated thunderstorms sweeping over West Auckland were expected to ease later this evening.
The large thunderstorms formed over the Waitakere Ranges and Manukau Heads area, WeatherWatch said.
The forecaster warned that the localised downpours could be heavy and may lead to rapidly rising streams.
Flash and surface flooding was also possible, WeatherWatch warned.
The heavy showers may spread further east this evening, developing stretches of heavy showers along the entire western Auckland coastline.