Weather: It's going to be warm, humid - and wet

Traffic in the wet weather. Photo / John Borren

Make the most of a bright morning tomorrow because the weather is expected to disintegrate across the North Island as the day wears on.

After a warm and humid start, showers - some heavy from Waikato northwards - will hit in the afternoon.

"Occasional showers will drift southward during the day, with the east coast getting the worst of the cloud and rain," MetService forecaster April Clark said.

A ridge should spread over the southern South Island on Monday and Tuesday as a low approaches New Zealand from the northwest Tasman Sea.

"In the north, Taranaki and Hawkes Bay will have showers and rain," Clark said. "Heavy falls are possible."

There is not much sign of improvement as the week wears on.

On Tuesday there will be more rain in the North island, with heavy falls possible from Waikato southwards.

In the South Island there will be patchy drizzle in the north and west, turning to rain north of Kaikoura and Westport with heavy falls but bit should be mainly fine elsewhere.

The low centre should cross New Zealand on Thursday followed by south to southwest flow. A period of rain is expected over most of New Zealand as this system crosses the country.

"The risk of rainfall amounts reaching warning levels is low for Gisborne on Tuesday but moderate for the North Island from Taranaki to Hawkes Bay southwards for Tuesday and Wednesday," Clark said.

A moderate risk of warning amounts of rain extends over Marlborough, Nelson, Buller and northern Westland on Wednesday and Thursday while a low risk extends to southern Westland and also down the east of the South Island.

There is also a low risk of sustained heavy rain over the upper North Island from Taranaki to Bay of Plenty northwards on Thursday ahead of a cold front.

Further, easterly gales may develop over western parts of Nelson and over Buller and northern Westland on Tuesday and Wednesday and there is a low risk the winds may reach severe gale force.