"In addition, heavy rain is likely in the west of both islands, the central North Island hill-country, and the eastern Bay of Plenty," Ms Blades said.
A cold and showery southwesterly change was expected to follow the front, bringing a wintry blast through Wednesday and Thursday. In the far south, showers were likely to fall as snow in altitudes from 500m above sea level.
The ridge of high pressure would start building on Thursday, ushering in a dry end to the week for most of New Zealand.
Your Monday forecast
•Whangarei: Sunshine interspersed with showers. Easterly breezes. Low 8C, high 15C
•Auckland: Mainly fine, afternoon showers possible. Southeast fizzles out. Low 9C, high 15C
•Hamilton: Fine with gentle breezes. Low 3C, high 15C
•Tauranga: Fine. Morning southeasterlies, then light winds. Low 6C, high 15C
•Hastings: A few morning showers, clearing to fine afternoon. Southeast dies. Low 1C, high 13C
•New Plymouth: Sunshine and gentle breezes. Low 6C, high 14C
•Palmerston North: Fine, apart from morning cloud. Light winds. Low 3C, high 15C.
•Wellington: A sunny day. Gentle breezes. Low 7C, high 12C
•Christchurch: Mainly fine, morning cloud or fog. Freshening northeasterlies. Low 5C, high 15C
•Dunedin: Mainly fine. Northeast freshening later. Low 7C, high 13C
Your Tuesday forecast
•Whangarei: Cloud developing, drizzle at times. Low 10C, high 17C
•Auckland: Becoming cloudy. Drizzle and northerlies developing. Low 10C, high 16C
•Hamilton: Cloud increasing, late drizzle. Northerlies developing. Low 7C, high 15C
•Tauranga: Occasional drizzle and northerlies developing. Low 10C, high 15C
•Hastings: Fine, high cloud later. Northerlies developing. Low 7C, high 16C
•New Plymouth: Becoming cloudy, rain at times. Northerly strengthens. Low 9C, high 14C
•Palmerston North: Cloud increasing. Northerlies strengthening. Low 7C, high 16C
•Wellington: Fine spells, with a few showers. Gusty southeasterlies. Low 9C, high 13C
•Christchurch: High cloud increasing. Fresh northeast dying out. Low 4C, high 16C
•Dunedin: Cloud increasing, brief rain. Dying northeasterlies. Low 4C, high 14C
(Source: MetService)