Thunderstorms and downpours are on the cards for Auckland and elsewhere in the top of North Island, with severe weather alerts issued for tomorrow.

MetService forecaster Thapi Makgabutlane said a low-pressure system, arriving from the northwest on Thursday, would bring with it a surge of warm, moist air.

Rain radar map projections showed the entire North Island engulfed by rain clouds by 4pm tomorrow before continuing to move east overnight.

MetService has issued heavy rain watches for eastern Northland, the Coromandel Peninsula, Bay of Plenty and Gisborne/Tairāwhiti, lasting from 4am to 6pm.

The forecaster said there was a chance it would have to upgrade these watches to warnings.

“The influx of warm, humid air increases the potential of impactful downpours within a broader band of rain,” MetService said.

In Auckland, rain was forecast to develop in the morning and turn to showers in the afternoon. Thunderstorms and localised downpours were also possible, MetService said.

The daily high in the city was forecast to hit 22C while it was expected to drop to 18C tomorrow night.

Auckland’s rainfall will likely be followed by cloudy, humid conditions on Friday, with temperatures forecast to reach 26C.

Other northern centres were similarly forecast to experience warm and muggy weather on the back of the system, with Whangārei and Hamilton both forecast to hit 27C on Saturday.

“We’re also looking at [overnight] temperatures in the mid to even high teens for that part of the country ... so there are some muggy nights ahead.”

A separate front arriving in the west and south of the South Island also posed a low chance of severe rainfall for Fiordland and the far south of the Westland District.

That’s been a familiar picture since spring, with high pressure to the northeast and low pressure to the southwest driving a succession of rainy, westerly fronts onto New Zealand.

For eastern regions like Hawke’s Bay, where these westerly winds have arrived stripped of moisture, the result has been parched soils and high fire danger.

Coastal areas of Hawke’s Bay now met the criteria for drought, while swathes of the region were classified as very to extremely dry.

The region is forecast to get scorching hot temperatures this week, with the mercury to reach 30C in Hastings on Friday and Saturday.

Raphael Franks is an Auckland-based reporter who covers breaking news. He joined the Herald as a Te Rito cadet in 2022.