Whanganui's dry autumn spell ends with a week of showers; heavy rain watch for Tongariro National Park

Whanganui is in for its first wet week of autumn as rain settles in for several days. Photo / Bevan Conley

Whanganui's dry autumn spell has come to an end as showers and westerly winds set in to dominate the week.

A heavy rain watch is in force for Tongariro National Park from Sunday morning and is expected to be in place until early on Monday.

MetService meteorologist Dan Corrigan said the weather was not expected to be dramatic in low-lying areas of the region.

"While there have been ridges of high pressure over the central North Island for the last few weeks, a slow-moving front has come in from the west bringing rain to the area," he said.

"Atmospheric pressure means the rain is heavier in the mountain ranges and things have been moving in a slight northerly direction so the severe rain warnings have moved from the Tararua ranges to Tongariro and Mt Taranaki."

Corrigan said showers, interspersed with cloudy periods, were set to continue throughout the week and there was the likelihood of some strong westerly winds later in the week.

"Whanganui had a very dry April with only 21.2mm recorded for the entire month and 15.2mm fell on one day - Friday, April 22.

"May has had a dry start as well so I'm sure the rain is welcome in the area."

Despite the rain, temperatures will remain above average for the time of year with average highs of 21C until Thursday when a high of 17C is forecast followed by 16C on Saturday.

"What's really notable are the mild overnight temperatures for the time of year," Corrigan said.

"Whanganui is really punching above the average there and the overnight lows are around 6C warmer than they would normally be in May."

An overnight low of 14C is forecast for Monday, 15C for Tuesday, 11C for Wednesday, Thursday and Friday before dropping to 8C on Saturday night.