Bay of Plenty residents can expect a warm and mostly sunny start to the week before rain spreads across the region from Wednesday.

Colder temperatures are also on the cards, MetService said in its latest weather update.

The weather organisation said much of New Zealand will enjoy settled conditions to begin the week, with a strengthening northwesterly airflow expected to push temperatures above the average across many eastern parts of the country.

While the warmest conditions are forecast for Hawke’s Bay and Canterbury, where temperatures could reach the high 20s, Bay of Plenty residents can also expect mild weather and warm nights through the first half of the week.

MetService meteorologist Maddy Neal said overnight temperatures would remain in the mid-teens for many areas, offering little respite from the daytime warmth.

“Temperatures are looking to soar into the high 20s for eastern areas of the country at the start of this week, with places in the Hawke’s Bay and Canterbury looking at a cracking 27 degrees Celsius on Tuesday,” Neal said.

The warmer conditions will not last.

A cold front is expected to move on to the South Island on Tuesday before tracking north on Wednesday, bringing rain and a marked southerly change.

As the system spreads up the country, wetter and cooler conditions are expected to reach Bay of Plenty.

Neal said the shift would be noticeable.

“As this front moves up the country throughout the week, warmer weather is going to be replaced by a wet winter chill. So, if you’ve put the winter duvet away already, it may be worth digging back out towards the end of the week.”

The rainfall may be welcomed in parts of the North Island, including Bay of Plenty, after a dry start to October left soil moisture levels below average.

Heavy rain watches have been issued for parts of the South Island, while strong northerly winds are also forecast for exposed areas of Wellington on Wednesday.

There is also the possibility of snow affecting some higher South Island passes and high-country farms later in the week as colder air spreads north.