After an extremely wet winter for a lot of the country, MetService is forecasting changeable weather as we head into spring with some cooler temperatures.

August rainfall records were broken in New Plymouth, Palmerston North, Wellington (Kelburn), Blenheim, Wanaka, and Nelson (also their second wettest month at any time of year since 1941).

More than 100mm of rain already accumulated at some West Coast stations in the 24 hours up to midday Thursday.

A front is quickly crossing the North Island with a splashing of rain and a change to cooler southwesterly winds.

Cooler air on the way from the south also brings a risk of snow down to 500 metres in the hills of Southland and Otago this weekend before high pressure moves in.

Temperatures are on a downward trend as the cold air spreads northwards, starting in the South Island where widespread frosts are forecast from Sunday morning heading into next week.

"Gore and Invercargill are looking at a high of only 8°C on Sunday with blustery westerlies, and most South Island towns will struggle to reach double digits in the afternoons early next week," says MetService meteorologist Dan Corrigan.

Meanwhile at the opposite end of the country, a low pressure system is forecast to cross the upper North Island during the second half of Monday.

"Monday's low pressure system is likely to bring a burst of heavy rain and strong easterly winds, though current data suggests it will move away to the southeast relatively quickly.

"We recommend people keep an eye on our website or app for any severe weather forecasts that may be issued closer to the time."