Auckland, Whangarei and Hamilton will hit 23C with some showers.
Metservice meteorologist Claire Flynn said a cold front would reach the lower part of the North Island tomorrow morning, but its strength will have weakened by the time it moves from the South Island.
"It's likely to bring some showers spreading north throughout the day. Ahead of the front it won't be too bad. For the likes of Auckland you'll probably have fine breaks throughout the day and showers in the evening, so not a bad day."
A cool change will brush Canterbury and bring with it a much cooler day- Christchurch drops from today's high of 27C to 16C.
On Sunday North Islanders can expect mostly fine weather with the odd shower left lingering. Temperatures will be in the early teens to early twenties.
"The temperature was above average this week for a few spots, but this cold front is bumping it back to average," Flynn said.
Late Sunday is when Kiwis could start feeling the cold as another cold front moves up from the South Island.
Aucklanders will feel some southwesterly breezes and are looking at 15C overnight.
Northerlies will also develop in Wellington on Sunday and temperatures will sit around 12C in the evening.
On Monday a big portion of the South Island will be 4 to 8 degrees cooler than usual, and Tuesday is when cooler temperatures will hit.
Auckland drops to 11C overnight on Tuesday, Wellington to 8C and Christchurch to 6C.
Main centre weekend forecasts
Whangarei
Fine breaks with showers and a high of 23C on Saturday. On Sunday party cloudy with chance of a shower.
Auckland
Saturday fine breaks, and chance of evening shower. 23C. Sunday a fine day.
Hamilton
Fine breaks, but an afternoon shower or two. Southwesterlies and a high of 23C. Sunday fine day with southwesterly breezes.
Tauranga
Fine, but chance evening shower or two. Southwesterly breezes with a high of 25C. Cloudy periods, and a morning shower or two on Sunday.
Wellington
Showers with a late morning southerly change that are clearing late afternoon. A high of 18C. Fine apart from morning and evening cloud on Sunday.
Christchurch
Cloudy with a few showers, becoming fine by afternoon. Southerlies dying out around midday. A high of 16C. Fine with high cloud and rain developing at night on Sunday.
Dunedin
A few late morning showers, then fine. Cloud returning evening. Westerlies and a high of 15C. On Sunday rain developing afternoon, clearing evening.
Queenstown
Fine, apart from morning and evening cloud. Light winds and a high of 16C. Cloud thickening and occasional afternoon rain on Sunday.
