UPDATED 4.51PM: A thunderstorm watch has been issued for the Bay of Plenty.

A line of wind convergence is expected in western parts of the Bay of Plenty from late this evening and then slowly drift eastwards overnight to reach eastern Bay of Plenty about mid-Friday morning.

Showers are forecast for the Bay of Plenty today and tomorrow.

The atmosphere is quite unstable and there is a risk of heavy showers forming on this line, says the MetService forecaster Paul Mallinson.

"This is an alert to the potential development of localised downpours, with or without thunderstorms, from about 10pm in western areas, drifting slowly east overnight as described. Rainfall rates of 25 to 40mm/hr are possible.

"Spot accumulations could range from 50 to 100mm over several hours, especially in coastal areas and there is a risk of up to 150mm over a four to five hour period.

"Rainfall of this intensity can cause flash flooding, especially about low-lying areas such as streams, rivers or narrow valleys, and may also lead to slips. Driving conditions will also be hazardous with surface flooding and poor visibility in heavy rain."

Earlier:

A few evening showers are on the cards for the Bay of Plenty tonight.

An active southerly change is moving northwards, bringing some showers and cooler weather to the east of the North Island.

Meanwhile, a ridge of higher pressure builds over the South Island bringing some sunny conditions.

Back in the Bay, the MetService is predicting some showers for tomorrow and cloudy conditions over the weekend.

Daytime temperatures will see daily highs sit around the 26 degree mark, with overnight lows varying from 14 to 18 degrees.

Ahead of New Zealand's Cricket World Cup clash with Australia at Eden Park at the weekend, MetService meteorologist John Law says: 'Weather-wise, it looks like a good day on Saturday in Auckland.

'Much of the day looks fine and dry with temperatures reaching the mid-twenties. There could be the odd shower showing up on the radar, but chances are Eden Park will stay dry.”

If you are not off to the cricket, there is still plenty on this weekend and the weather across the North Island looks dry for many.

'The ridge of high pressure remains over the North Island for most of the weekend, bringing settled conditions,” says John.

'However, a few showers are possible here and there across the more central parts of the North Island.”

A cold front moving north across the country at the start of next week looks set to bring a spell of rain to the South Island on Monday, before crossing Cook Strait and bringing some wetter weather to the North on Tuesday.