MetService says Rotorua will have early showers then rain developing in the morning, possibly heavy rain from afternoon. There will be strong northeasterlies, changing southwest in the evening.
Tauranga is expected to have rain in the morning, possibly heavy, as well as strong northeasterlies, changing southwest in the evening.
Heavy rain warnings have been issued for Northland, the northwest ranges of Nelson and the ranges of Westland.
In Northland, the alert is in place until at least 3pm. People in the area are being told to expect between 50mm to 70mm of rain to accumulate - especially about the eastern hills.
MetService said peak intensities would be between 10mm to 15mm per hour this morning.
"Heavy rain may cause streams and rivers to rise rapidly. Surface flooding and slips are possible and driving conditions may be hazardous," a spokesman said.
There was also a strong wind watch in Northland in the early hours of this morning - with winds turning into severe gales at times.