The North Island east coast from Gisborne south looks set for a day or two of decent rain, MetService says.
But there's little relief expected for most of the large swathe of dry land across the centre of the island.
MetService is offering some hope for rain in coastal Bay of Plenty tomorrow, with only a slender possibility of that rain spreading into the rest of the Bay of Plenty and northern Waikato.
In the Hawke's Bay coastal hills and ranges, and the coastal hills south of Gisborne city, rain is expected to become heavier this afternoon, and not ease until tomorrow evening, MetService said.
Between Napier and Gisborne cities, up to 200 millimetres could fall in 32 hours, with up to 150mm elsewhere in the area.
Heavy rain was also expected in remaining areas of Gisborne, and about the coastal hills and ranges of Wairarapa, today and tomorrow. Some rain could continue through to Friday.
The rain was the result of a complex low pressure system forecast to move slowly across the upper North Island through the week, MetService said.
For coastal Bay of Plenty, there was a moderate risk of thunderstorms with heavy rain up to 25mm an hour tomorrow afternoon and evening. For inland areas of Bay of Plenty, northern Waikato and Coromandel Peninsula the chance of thunderstorms and heavy rain was only low.
Wellington, which will host the Duke and Duchess of Cambridge and baby Prince George for the next three days, was smothered in low cloud and drizzle this morning, with rain expected tomorrow and Wednesday.