Metservice meteorologist Claire Flynn said a cold front would reach the lower part of the North Island today, but its strength would have weakened by the time it moved 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 would brush Canterbury and bring with it a much cooler day than yesterday - Christchurch drops from yesterday's high of 27C to 16C.
Tomorrow North Islanders could expect mostly fine weather with the odd shower left lingering. Temperatures would 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."
Late tomorrow is when Kiwis could start feeling the cold as another cold front moves up from the South Island.
Aucklanders should feel some southwesterly breezes and is looking at 15C overnight.
Northerlies will also develop in Wellington tomorrow 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 forecasts
Whangarei
Fine breaks with showers and a high of 23C.
Auckland
Fine breaks, and chance evening shower. Southwesterlies and a high of 23C.
Hamilton
Fine breaks, but an afternoon shower or two. Southwesterlies and a high of 23C.
Tauranga
Fine, but chance evening shower or two. Southwesterly breezes with a high of 25C.
Wellington
Showers with a late morning southerly change that are clearing late afternoon. A high of 18C.
Christchurch
Cloudy with a few showers, becoming fine by afternoon. Southerlies dying out around midday. A high of 16C.
Dunedin
A few late-morning showers, then fine. Cloud returning evening. Westerlies and a high of 15°C.
Queenstown
Fine, apart from morning and evening cloud. Light winds and a high of 16C.