MetService says bursts of heavy rain are possible and some downpours may reach warning criteria.
This morning Auckland Transport cancelled all Gulf Harbour ferries because of bad weather and replacement buses will take passengers between Auckland and Whangaparaoa.
Further south slips have closed several roads across the Whanganui region.
Council crews are clearing debris from four roads after heavy rain lashed the region this week.
Manawatu Wanganui Civil Defence said Kauarapaoa and Creek Rds were expected to be re-opened by lunchtime.
Burma Hill Rd on the Mangamahu side was closed but debris was expected to be cleared by the end of the day.
Crews were also clearing a fourth slip affecting Mangamahu Rd but it was not known how long the operation would take.
Today's forecast
Auckland: Occasional rain, clearing this morning. Fresh southeasterlies. 14C
Hamilton: Cloudly, showers then fine. Southeasterlies weakening. 15C
Tauranga:Morning showers then fine. Southeasterlies easing at night. 14C
Wellington: Cloudy, showers. Fresh southerlies. 9C
Christchurch:Cloudy, showers, light winds. 8C
Dunedin: Morning cloud then fine. Northeast breezes. 8C