A new report says soils are drying out in parts of the North Island, with some regions drier than usual for this time of the year.
NIWA's weekly soil moisture report assesses severely to extremely dry conditions.
Regions experiencing these soil moisture deficits are deemed 'hotspots' with persistent hotspot regions having the potential to develop into drought.
The latest report said there had been notable decreases in soil moisture levels across the North Island, from Northland to Waikato, including the Coromandel Peninsula.
Smaller decreases were recorded from Bay of Plenty to Gisborne and the Central Plateau.
However, the report said there had been little change in the lower North Island.
"The driest soils across the North Island compared to normal for this time of the year were found in southern Northland, northern Auckland, much of the Coromandel Peninsula, the Hauraki District, and coastal Wairarapa," it said.
The wettest soils for this time of the year were in coastal Taranaki and the Kapiti Coast.
In the North Island, decreases in soil moisture had led to the expansion of hotspot coverage in the past week, particularly in the upper portions of the island.
Hotspots are now in place in southern Northland, northern Auckland, Hauraki District, the eastern Coromandel Peninsula, and most of the East Coast from Mahia Peninsula south to Wairarapa.
Across the South Island, substantial rainfall during the past week led to significant soil moisture increases along the West Coast from Tasman to Fiordland, as well as in Stewart Island.
Conversely, the eastern South Island generally saw light to moderate soil moisture decreases as rainfall was meagre.
The driest soils across the South Island compared to normal for this time of the year are found in coastal Hurunui District, while the wettest soils for this time of the year are found in upper Fiordland and the western Queenstown-Lakes District.
"Due to the recent soil moisture decreases in the eastern South Island, hotspots are now in place from the east coast of Marlborough to the Hurunui District, as well as a small portion of coastal Timaru District."
Authorities in Waikato were already planning for possible water shortages.
Hamilton City Council’s city waters manager Maire Porter said despite recent rain, it was important to conserve water to prepare for the long, dry summer ahead.
"We’ve already seen a steady increase in water demand over the past month. Historical trends indicate that with improving weather, water use will only continue to increase throughout December," she said.
Waipa District Council’s water services manager, Martin Mould, said a hot summer was on the cards but a wet spring season was keeping water alert levels at bay.
"Te Awamutu and Pirongia’s water supply comes from the Mangauika Stream. In the summer months, it can struggle to keep up with demand so we are advising people be mindful of how they use water, particularly over summer."