Bay of Plenty residents are being urged to rug up as a persistent southerly blast delivers colder temperatures, widespread frosts and a wintry feel across the region this week.

In its latest weather update, MetService said a large high-pressure system in the Tasman Sea is driving cold southerly winds across much of New Zealand, with temperatures expected to remain in the low to mid-teens through the first half of the week.

While the weather is expected to stay largely settled and sunny across much of Bay of Plenty, overnight temperatures are forecast to drop sharply, creating widespread frosts and the potential for black ice on roads and footpaths in some areas.

Meteorologist Alanna Burrows said the southerly airflow was pulling cold air directly from the Southern Ocean.

“We all expect colder temperatures in winter, but when the wind is coming from the south, straight off the Southern Ocean, the chill is more dramatic,” she said.

The cold snap is expected to affect much of the country, with showers at times for eastern districts and moderate to heavy southerly swells along exposed coastlines.

Although Bay of Plenty residents can expect plenty of sunshine between chilly starts, farmers, growers and motorists are being advised to keep an eye on forecasts as frosts become more widespread overnight.

The southerly is forecast to ease from Thursday as the high-pressure system moves over New Zealand, bringing calmer conditions. However, clear skies and light winds are expected to create ideal conditions for another round of frosts before temperatures begin to climb again.

A warmer northwest flow is forecast to develop on Friday, lifting temperatures and signalling the end of the cold outbreak, although rain is expected to return to western parts of the country later in the week.