MetService forecaster Allister Gorman said a large ridge would bring fine and hot conditions to most parts this week.
"Generally, today is a lot more settled. We do have a few showers over the North Island, but there's a lot of fine weather over most of the country.
"We've got this large ridge over the country. At the present, we don't have any warnings out. There's a possible risk of thunderstorms south of the South Island and a bit of rain coming in to the far south too."
Whangarei will be mainly fine today, with a chance of showers and a temperature high of about 26C. The odd shower is also expected tomorrow and there is a possibility of heavier rains on Friday.
Tauranga also has similar conditions -- mostly fine, with morning cloud and a high of 26C -- as does Wellington. Christchurch is also expecting a very fine day and temperatures reaching 25C today.
Mr Gorman said the country was in "a very humid situation" at the moment and the muggy conditions were set to stay around this week.
The warm weather would be particularly felt in central and eastern parts of New Zealand.
A low-pressure system is forecast to bring wet and windy weather to the North Island on Friday -- but also warm and humid air from across the Tasman Sea.
Further south, a front moving over the South Island on Thursday and Friday will lead to rain in the west of the island.
Today's forecast
• Auckland: Fine spells, chance afternoon shower, 27C.
• Whangarei: Mainly fine, chance shower, 26C.
• Tauranga: Morning cloud then fine, 26C.
• Wellington: Fine. Some morning cloud, 24C.
• Christchurch: Fine. Light winds, 25C.