A chance of heavy and thundery rain is being predicted for the Bay of Plenty today, with a high of 20C on the cards across the city.

Further afield, rain is forecast to develop in Auckland and could be heavy and thundery.

The MetService says there is a chance of heavy rain and thunder for the Bay of Plenty today. Image: MetService.

Meteorologist Rob Kerr says the ridge that brought settled conditions at the beginning of the week is moving off the country.

He says northwesterlies will push scattered rain across parts of the North Island.

'In fact, northwesterlies delivering warm, moisture-laden air from the north Tasman Sea will be the theme of the week for New Zealand, splitting the country in two: cloudy and wet in the west, and warm and dry in the east.

'Rain and strong northwesterlies are expected to sweep over the North Island during Saturday, while a colder change moves over the South Island.

'Conditions ease dramatically later on Sunday as a ridge builds over the country,” says Rob.